Buyer Beware? Hot Starts and Fantasy Baseball Waiver Wire Analysis (Week 7)

Ryan Kirksey's fantasy baseball waiver wire analysis for Week 7 (2024), and whether to buy/sell MLB hitters and pitchers. Should you be leery of these hot streaks?

With the weekend upon us, a fresh batch of fantasy baseball waiver wire recommendations will be filling the RotoBaller feeds. Our team's various waiver wire recommendations are coming with full force this weekend so be sure to check out all the great articles. But as we consider players who are in the midst of hot streaks or expanded roles on their teams, there is always a buyer beware element to our decisions.

Are hot streaks a result of luck or a change in skills or roles? Will today's costly waiver wire investment just end up on tomorrow's most-dropped list just because we were trying to chase an unsustainable set of statistics? Evaluating the hot waiver wire recommendations for their under-the-hood performance will help fantasy managers further understand not only should they make an investment in certain players, but also how much of an investment should be made to acquire their services.

Below are four players who are widely recommended as waiver wire options across the fantasy baseball industry this weekend that deserve a closer look. It's not to say that these are not strong options for your own teams considering the context, but each deserves a closer look based on their recent performance.

Willi Castro, Minnesota Twins

Willi Castro has proved to be the super-utility spark that the Minnesota Twins have needed to roll off an 11-game winning streak and tie for the AL Central lead. Castro played third base until Jose Miranda came up. He played shortstop while Carlos Correa was injured, and now he is playing center field with Byron Buxton landing on the IL. Along the way, he has accumulated a .282/.348/.466 line with a couple of home runs and three steals, plus 15 runs. The playing time for Castro looks secure considering the state of the Twins' roster, but I'm not convinced the elite-level performance will follow.

The first thing that jumps out for Castro is his strikeout rate and walk rate, particularly as they compare to 2023. His 29% strikeout rate is five percentage points higher than last year and his 6.9% walk rate is 1.5 percentage points lower. He is making the same amount of contact as last season, but his first pitch strike percentage and his called strike percentage have all jumped up. In addition to those, Castro's batting average on balls in play (BABIP) is .397, the sixth-highest number in the league. The league average for 2024 is currently .288.

Nine-game hitting streak for Willi Castro, a new career-high.

Since the start of the winning streak, he is 19-for-44 with a homer, 2 triples and 7 doubles while slashing .432/.444/.750 for an 1.194 OPS in that stretch.

— Do-Hyoung Park (@dohyoungpark) May 4, 2024

"But Willi Castro is fast, and fast players have higher BABIPs!" you scream. Yes, that's true, and it's true Castro did have 33 steals last season compared to five times caught stealing. But is he actually that fast? His 27.9 ft/sec sprint speed is just 16th among shortstops and would be 31st among center fielders. He was more of an opportunistic base stealer last season rather than a burner, so I'm not counting on his speed saving a bunch of hits on would-be outs going forward.

Tyler Nevin, Oakland Athletics

Tyler Nevin is essentially a journeyman at this point. He has played for three teams in his four Major League seasons and has a career .229/.323/.344 slash line as a very part-time player. He has nine career home runs and one career stolen base (four of those homers and that steal are from 2024), so the fact that he is crushing the ball right now in a full-time role for Oakland must give us some hesitation. Nevin was a 38th-overall pick back in 2015, but until now he has not done anything to prove he is the batter he's been in 2024.

So far, Nevin is hitting .313/.370/.482 after coming over from Baltimore to Oakland. He is playing full-time because of injuries to Zack Gelof and J.D. Davis and Nick Allen was recently sent back to the minors instead of Nevin, assuring his playing time for now. Nevin looks good on paper this season, but it looks completely unsustainable when we start digging into the underlying numbers.

Nevin's BABIP is .361 (career .284), and his walk rate dropped from 10.8% last season to 5.4% this year. But perhaps his biggest problem this year is his lack of loft and lift in his batted balls. His launch angle is down five percentage points from last season (13.7 degrees to 8.9 degrees) and he is hitting the ball on the ground 45% of the time. The balls he does hit in the air have an outlier-like 18% home run to fly ball rate (10.6% is average). All of it adds up to some negative regression coming and I wont' be investing this weekend.

Connor Wong, Boston Red Sox

You won't find many players with a wilder discrepancy between what Connor Wong is actually doing to date at the plate and what the projection systems say he will do the rest of the season. Currently, Wong is slashing .351/.380/.595 with five home runs in 22 games. Steamer projections look him to hit just .241/.292/.400 for the rest of the season with only nine more home runs. What are factors leading to such a wide gap in actual versus expected performance? In reality, there are many.

How ridiculous has Connor Wong been so far?

He now has the 2nd-best wRC+ and OPS amongst all catchers this season (minimum 70 PA). Both barely trail Salvador Perez.

75 PA - .366/.387/.620/1.006 - 5 HR - 3 2B - 14 RBI - .435 wOBA pic.twitter.com/d7lbjUglZv

— Tyler Milliken ⚾️ (@tylermilliken_) May 2, 2024

First, Wong has an unsustainable .396 BABIP through the first six weeks of the season. That number would be tied with Willi Castro for the sixth-highest rate in the league if Wong had enough plate appearances to qualify. There is a reason why players from the Rockies, Red, and Phillies make up most of the top ten on that list. They play in home parks that are conducive to high hit rates and extreme offense. Fenway Park has a 105 park factor for hits in 2024, meaning it's just 5% above league average this year (and is 14% below average in home run park factor).

Wong's real numbers compared to his actual statistics are quite glaring as well, but paint a clear picture of what the projections systems are trying to show. Wong's xBA is just .248 and his xSLG is just .442 on the season. That's largely driven by a decrease in barrel rate, hard hit rate, exit velocity, and line drives since last year. Catcher has mostly been a wasteland position this season, but there is a case to be made that Connor Wong joins them all there very soon.

Erick Fedde, Chicago White Sox

After spending the 2023 season in the Korean Baseball Organization (and dominating over there), there has been a lot chatter that his time over there "fixed" Erick Fedde, which has led to his dynamic resurgence in 2024 with the Chicago White Sox. After never striking out more than 8.6 batters per nine innings in his first six Major League seasons, he is all the way up to 10.1 this year, mirroring his 10.4 from the KBO last year. His walks are at 2.34 per nine (3.68 for his career), and his 5.81 ERA in 2022 has been chopped in half so far this year (2.60).

Those are all good things, right? He will have a tough time winning many games with the White Sox, but those ratios and strikeouts are pristine. Many have pointed to the updated pitch mix for Fedde as a reason for his success. He has basically minimized his fastball usage this year (22%), and has significantly increased his sinker-slider combination (more than 59% of his pitches come from these two) and added a changeup (18%) that didn't exist in his first MLB stint. However, despite all the positive changes, there are some signs that his performance could be driven by a bit of luck.

Erick Fedde's 9th K. pic.twitter.com/gs4ALVPYPi

— Rob Friedman (@PitchingNinja) April 28, 2024

First, Fedde's BABIP allowed is a very-low .253, or 50 points below his career average. In fact, that number is top 30 among all starting pitchers Second, when Fedde does allow men on base, he is simply not letting them score. His 91.2% left-on-base percentage is the sixth-best in baseball, a full 20 points better than league average. That number is sure to regress, which will drag his ERA down with it. Fedde's xERA (3.20) and his FIP (4.00) are not terrible by any means, but neither scream "Ace!" when looking deeper into Fedde's performance.

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