A Tale of Two Months: Outfielders

With nearly three months now in the books, and most players having played nearly as many games as they did in 2020, it's time to take stock on the truth behind various hot starts and slumps.

However, we shouldn't do so just for our own edification, as there is good instruction to be had. Knowing who to target and who to trade away; who can be relied on for the future and who you need to have backup plans for. Don't wait until right before the trade deadline to start making moves. The time is now.

With that in mind, we're going to go around the positions, using the biggest differences in wOBA between April and May as our jumping-off point. And since we're now a few weeks in, we might as well include June too. After covering first base, second base, third base, and shortstop, it's time to get on the grass. Let's find some truth in spring advertisements, shall we?

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Outfielder wOBA Changes

First, a few parameters and explanations. We'll use a minimum of 50 PA in each of April and since May 1 as our cutoff and players will be sorted according to change in wOBA. All stats are through the weekend and all values mentioned are from the FanGraphs auction calculator, using settings for a 12-team league with: C (1) - 1B (1) - 2B (1) - SS (1) - 3B (1) - OF (5) - MI (1) - CI (1) - UT (1).

Regardless of whether a player's wOBA has gone up, down, or stayed the same, that change doesn't tell the whole story, so we'll try to get a better sense of the whole picture using fantasy value breakdowns and a variety of advanced stats. And pictures, too!

Speaking of which.

The Good

Ryan Mountcastle, 1B/OF, BAL ($14.5, OF 23)

254 PA: 12 HR - 30 R - 40 RBI - 3 SB - .266/.291/.473

Remember when people were starting to be concerned about Mountcastle, one of Baltimore's top prospects, after a brutal April? If those days weren't gone before this last weekend, they certainly are now, after hitting five home runs in three games, including a triple dong on Saturday versus Toronto.

Mountcastle has finally started tapping into his power potential, pulling the ball in the air far more often, with his 32.5% FB% (does not include pop-ups) and 44.0% Pull% in 2021, up from a 21.4% FB% and 29.6% Pull% over his 140 PA debut in 2020. Granted, his .266 AVG is down from a .333 AVG last season but a .266 xBA in 2020 spoke to that being illusionary.

His x-stats aren't as inspiring, with a .336 xwOBA and .470 xwOBAcon (wOBA on contact) since May 1 showing large gaps compared to a .385 wOBA (-.049) and .544 xwOBAcon (-.074). However, I believe in giving more leeway on these things when looking at players who play at an extreme hitter's park.  Ten of Mountcastle's home runs have come at home and according to Baseball Savant, he would've matched his total of 12 HR at only 10-of-30 stadiums. Simply put, more batted-ball "luck" is going to come your way when playing in a bandbox like Camden.

Especially when you're as aggressive as Mountcastle has been in 2021 on hittable pitches in the zone. While his overall swing rate has stayed virtually the same (58.8% Swing% in 2020, 58.0% in 2021), he's increased from a 76.9% Meatball Swing% in 2020, to an 88.1% MB Swing% in 2021. His 81% Swing% in the heart of the zone is down from 84% in 2020 but is still well above the league-average of 73% and his 67% Swing% in the shadow zone is down from 72% (53% league average).

However, as his 30.7% K% (8th-percentile) and 3.1% BB% (2nd-percentile) speak to, Mountcastle is still far too aggressive out of the zone, a story that's not fully told if looking only at a 42.2% Chase% that is only up two points from 2020. Remember that Chase% measures solely swings on balls out of the zone but Savant also allows us to parse things further by splitting a batter's entire zone into four areas; the aforementioned heart and shadow zones, as well as chase and waste zones:

Cutting his Chase% up further, we can see that he's risen from a 30% Swing% in the Chase zone (22% league average) and an 8% Swing% in the Waste zone (6% league average) in 2020 to 36% and 13%, respectively, in 2021.

Whether Mountcastle can continue to succeed with his free-swinging ways, remains to be seen but I'm partial to fly-ball hitters with pop who play in a miniature home park and in an offensive-friendly division. After this latest home run outburst, the "buy-low" ship has sailed for Mountcastle but be aware that he's still somehow available in over 30% of Yahoo leagues and 25% of ESPN leagues. Go check if he's around, just in case.

Kyle Tucker, OF, HOU ($22.9, OF 9)

265 PA: 13 HR - 42 R - 43 RBI -.268/.326/.506

Speaking of a buying low window slamming shut, let's give a quick word to how Tucker is now entrenched as a top-1o outfielder and giving five-category production. And mind you, that's with a .268 AVG that is backed by a .330(!) xBA that is in the top-1% of baseball. Tucker has posted an impressive .411 wOBA, .969 OPS, and .465 wOBAcon since May first but his x-stats have been even better; he has a .454 xwOBA, .521 xwOBAcon, and 1.083 xOPS over that same time.

If they exist, I'd take any reasonable buying opportunity I could find on Tucker, as once his batting average catches up with the ball-striking, his fantasy value will blow up that much more.

Hunter Renfroe, OF, BOS ($7.1, OF 40)

235 PA: 8 HR - 35 R - 31 RBI - 0 SB - .257/.315/.430

Poor Hunter Renfroe is playing every day on a good offense, is the #40 OF in 12-team leagues, but is still available in 80% of leagues on Yahoo and 70% on ESPN. Eight home runs is certainly less power than we've come to expect from Renfroe but he's also been more of a line-drive hitter in 2021, posting a career-high 27.0% LD%, with a 22.1% FB% that's down only slightly from 24.4% FB% in 2020 - and a far cry from 32.9% FB% he had in 2019, hitting a career-high 33 HR.

The lack of fly balls is hurting his power but Renfroe isn't being helped any by a career-low 12.9% HR/FB. And in addition to the big increase in wOBA, his .282 wOBAcon in April has also risen to a .465 wOBAcon since May 1, with his .454 xwOBA and .521 xwOBAcon since then both speaking to deserving even more success than he got.

Renfroe is boring and unexciting but is well above replacement in 12-team leagues, even if the previous power hasn't shown up yet. However, considering how well he's hitting the ball (and the current crackdown on pitchers) don't be surprised some of that old power shows up over the summer. Once again, widely available.

Other Improvements to Buy

• Justin Upton, LAA
• Tyler O'Neill, STL
• Bryan Reynolds, PIT
• Trey Mancini, BAL

The Bad

*Well, it looks like we have confirmation that Mike Trout is washed. You should immediately trade him...But only if we play in a league together. 

J.D. Martinez, OF, BOS ($27.0, OF 5)

286 PA: 14 HR - 48 R - 44 RBI - .309/.367/.552

Martinez is still the #5 outfielder by earnings, carrying an impressive line but know that a lot of his fantasy hay got made during an otherworldly April, hitting nine home runs and running a .351 AVG, while scoring 21 runs with 25 RBI in just 25 games. However, in his 41 games since, Martinez has just 5 HR, 23 R, and 16 RBI, dropping to a .285 AVG, while his .329 wOBA and .764 OPS are nowhere close to the .490 wOBA and 1.175 OPS he had in April.

Looking at his wOBA on contact, Martinez had a (once again, out worldly) .611 wOBAcon in April that's dropped to a very pedestrian .407 wOBAcon since May 1. But his x-stats say he deserved quite a bit less than he got in April, with a .486 xwOBAcon - which is still excellent but not a .611 wOBAcon - and a .407 xwOBA. And Martinez may still have an elite hit tool but that .333 AVG in April was backed by a more realistic .288 xBA, which makes his .285 AVG since May 1 look not very surprising.

The batting average expectations are the first thing you need to keep in check when evaluating Martinez going forward because a .288 xBA in April and a .292 xBA since May 1, paints a pretty clear picture of a .290 hitter. Which is fine! Just be aware of what you're likely to get for the remainder of the year.

Bryce Harper, OF, PHI ($7.2, OF 39)

211 PA: 8 HR - 32 R - 18 RBI - 5 SB - .274/.384/.464

From actual stats to expected ones, Harper has fallen off of a cliff since the start of May. His .447 wOBA and .522 xwOBA in April have dropped to a .301 wOBA and .314 xwOBA since, with a .525 wOBAcon and .643(!) xwOBAcon dropping to a .390 wOBAcon and .411 xwOBAcon. And that's not all; .321 AVG and .364 xBA in April? Down to a .238 AVG and .226 xBA. A .295 ISO then? A .109 ISO now. And just for fun, his OBP has also dropped over 100 points, with his SLG dropping over 250 points. That is some serious cliff diving.

However, remember that Harper not only got hit in the face with a baseball on April 28 but that same ball also bounced off his wrist, causing more damage than originally reported. He returned to action on May 2 but was obviously still hurting all month, eventually going on the IL on May 25. That's a lot of time to play with a balky wrist and goes a long way to explaining Harper's troubles.

Harper has been much better since returning from the IL on June 5 but is still struggling in the power department, hitting one home run in 49 PA, with a .386 SLG and .114 ISO. That makes just two home runs in his 115 PA since being hit, with an 88.1 mph average EV that is down from 93.5 mph prior to taking the face ball.

We've seen this time and time again; regardless of how soon they come back, wrist injuries tend to linger, particularly when it comes to power. And not helping matters is how impatient Harper has been since, with his 19.8% K% and 16.7% BB% prior to being hit, dropping to an 11.3% BB% since, with a 31.3% K%.

I'd say that this presents a buying opportunity for Harper, as normally the power comes back the further a player gets away from a wrist injury. However, I'm also given pause considering that he played hurt for nearly a month before going on the IL. But I'm an optimist and would thus be happy to acquire him if any sort of discount presents itself. The plate discipline didn't just disappear forever and even with the lack of power, Harper has started heating up recently, slashing .346/.370/.423 over his last seven games, with a 14.8% K%.

The Meh

Nick Castellanos, OF, CIN ($28.9, OF 3)

287 PA: 13 HR - 47 R - 38 RBI - 2 SB - .341/.394/.583

The .225 AVG of 2020 is a thing of the past and the fantasy dominance is real and spectacular. Castellanos is getting his fantasy goodness from everywhere except stolen bases (and even there, he's not a total zero) but his .341 AVG is carrying the day. He leads the National League in average (leading the .335 AVG of teammate Jesse Winker) and trails only the .350 AVG of Michael Brantley in the overall race. It's hard to expect him to stay at such lofty heights for the whole year but don't assume it's illusionary because you see his .397 BABIP; Castellanos has a .319 xBA that's in the top-2% of baseball.

Part of his success may lay with a return to his aggressiveness, as Castellanos has a 54.8% Swing% (roughly where it was in 2018-19) this season after dipping to 51.8% in 2020. More telling is a 78.7% Zone Swing% that is up from 73.2% in 2020 and 74.7% in 2019, with an 82.1% Zone Contact% that is up two points over 2020 and is second for his career only to a ridiculous 85.9% in 2019.

Chopping up those zone rates further, Castellanos has been an absolute heartbreaker, with an 84% Heart Swing% (73% league average) that is up from 76% in 2020 and 79% in 2019:

Looking at his batted-ball results on pitches in the heart, we see what a good idea this is for Castellanos - and where some of his bad luck came from last season. In 2020, he had a paltry .392 wOBA on contact on pitches in the heart, with a 0.23 run value (per 100 pitches) but that came with an excellent .609 xwOBAcon. In 2021, Castellanos has a .605 wOBAcon (.550 xwOBAcon) on pitches in the heart, with a 2.0 RV/100.

Don't throw all caution to the wind if considering acquiring him, however, as there are a couple of flags that should be noticed. For one, don't just expect pitchers to continue throwing balls in the heart as Castellanos continues smashing them. Adjustments will be made and his aggressiveness on lesser pitches may be leveraged. And while he's posted a career-low 19.9% K%, it's backed with a 15.2% SwStr% that speaks to more strikeouts coming.

Those are just things to keep in mind, though. Given the skills (and the home ballpark), I expect Castellanos to continue to be one of the safest sources of fantasy production for the remainder of the season.

Cedric Mullins II, OF, BAL ($28.1, OF 4)

308 PA: 13 HR - 40 R - 25 RBI - 12 SB - .314/.384/.544

All hail top-five outfielder, Cedric Mullins of Baltimore, second of his name and first in the Charm City's heart. Mullins has blown up in 2021, setting career highs virtually everywhere you can look and returning five-category fantasy production.

Mullins is a case where we need to do further evaluating of his surface stats, as some things don't tell the whole story, given his particular skillset. Even though his average launch angle has dropped slightly, from 15.6 degrees in 2020 to 14.5 degrees in 2020,  Mullins has seen a dramatic decrease in his groundball rate, after posting rates over 50% prior to 2021. He has a 41.7% GB% in 2021 that's down from 51.4% last season, with his fly ball rate increasing from 15.0% FB% to 29.2% FB%. Given his home park, hitting the ball in the air is almost always a good thing, particularly as the weather continues to warm up.

He's also making far less weak contact, as tracked by Baseball Savant, with a 6.0% Weak% that is a large drop from the 17.8% Weak% that he posted in 2020. His x-stats haven't been nearly as good as reality, running a .346 xwOBA and a .388 xwOBAcon on the year that is far away from his .401 wOBA and .466 wOBAcon. But as mentioned previously in regards to teammate Ryan Mountcastle, more "luck" tends to come your way when you play your home games at a high school stadium. However, unlike Mountcastle, Mullins also has the added bonus of elite speed, which can help increase that "luck" even more.

His .271 xBA says the .314 AVG is likely to come back to Earth but while I don't expect Mullins to be a top-five outfielder all season, the overall skills - combined with his leadoff spot and home park - don't lead me to believe that a big cliff is coming.

The Unmentioned

These are the players who didn't meet one of the minimum plate-appearance thresholds for either April or since May 1, but for your own edification, here they are. Take all changes with large grains of salt. Also, pour one out for poor Byron Buxton.

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