Overvalued, Undervalued Trade Targets - Buy/Sell for Fantasy Baseball (Week 6)

Trade candidates to buy or sell in fantasy baseball after Week 6 of the 2023 MLB season. Ben Rosener lists overvalued and undervalued players to target or trade away.

Making the right trades can be crucial to championship success in fantasy baseball, almost as much as the draft, if not more. While most trades can have a significant impact on your fantasy team, it’s the deals where you acquire undervalued players and then see their production improve that can really tip the scales in your favor where the standings are concerned.

The same can certainly be said about trading away players at the right time when they have the most fantasy trade value. Those deals could happen in the second week of April or the last week of August, but they’re impactful all the same.

Here are some undervalued candidates to pursue in trades and some overvalued ones who you should consider dealing for if they presently occupy a spot on your roster.

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Undervalued Players To Trade For

Tyler O'Neill, St. Louis Cardinals

O'Neill looks locked into a somewhat regular role for the Cardinals. Lately, Lars Nootbaar has been the only constant in the St. Louis outfield, with two of O’Neill, Dylan Carlson, and Alec Burleson starting alongside him. That role, and something resembling close to consistent plate appearances, is certainly good news for O’Neill, who looks primed for an uptick in production sometime soon.

The outfielder’s .241 average and .298 on-base percentage certainly aren’t ideal. Neither is a 34.0% strikeout rate, but there’s plenty to like about the type of contact the former Mariners prospect is making when he is putting the ball in play.

O’Neil’s barrel rate is decidedly above average, currently sitting at 14.5% on 55 batted balls so far. He’s also sporting a .453 xSLG as well as a 47.3% hard-hit rate. All three metrics rank in the 70^th percentile or better, with the barrel rate, in particular, sitting in the 85^th percentile. Elsewhere, the outfielder is back to obliterating fastballs much in the same way he did during his 2021 breakout season.

Tyler O’Neil vs Fastballs Since 2021

• 2023: .370 wOBA, .424 xwOBA, .500 slugging percentage, .622 xSLG
• 2022: .350 wOBA, .379 xwOBA, .437 slugging percentage, .487 xSLG
• 2021: .410 wOBA, .412 xwOBA, .579 slugging percentage, .594 xSLG

The flipside to that coin, unfortunately, is that O’Neill is struggling more against breaking stuff – more than last season when his numbers were a marked step down from his 2021 metrics.

Tyler O’Neil vs Breaking Balls Since 2021

• 2023: .195 wOBA, .246 xwOBA, .200 slugging percentage, .314 xSLG
• 2022: .275 wOBA, .290 xwOBA, .366 slugging percentage, .379 xSLG
• 2021: .351 wOBA, .367 xwOBA, .558 slugging percentage, .582 xSLG

It’s certainly something to keep an eye on moving forward, but as long as pitchers don’t attack O’Neill entirely with breaking stuff, he should be fine, especially where power production is concerned. It’s possible the manager in your league who drafted O’Neill, possibly in hopes of a bounce-back season, isn’t thrilled with his production so far.

If that’s the case, now’s the right time to float an offer their way and see if you can make a trade. The strikeouts may continue to a degree, but the slugger looks well-positioned, based on his advanced metrics, to be a reliable source of home run production for fantasy managers.

In fact, O’Neill is probably due for some positive regression in that regard, especially if he’s traded by the Cardinals this season. Of course, this is all entirely speculative and it’s probably a little too early to start looking at which Major League teams will trade veterans at the trade deadline, but the Cardinals currently sit at 10-21 and O'Neill is only controllable through the 2024 season, per Spotrac. Furthermore, the outfielder has an xHR number higher than his actual home run tally (two) in 13 of the league’s other 29 ballparks. An xHR number that is as high as five (Dodger Stadium) and six (Angel Stadium) in some venues.

Brent Rooker, Oakland Athletics

Much of the same logic that applies to acquiring Tyler O’Neill for your fantasy team now before a potential real-life trade occurs applies here to Brent Rooker as well.

Except the A’s might be baseball’s best bet to trade veterans this summer. Of course, this is, again, all entirely speculative, but Oakland sported a 6-24 record with a -118 run differential as of the beginning of play on Wednesday. The win total and particularly the run differential were both the worst in the league as of writing. No other team in the sport has reached a -100 run differential yet.

While Rooker hasn’t exactly struggled at home in the spacious confines of the Oakland Collesium, batting .306 with three home runs, a .278 ISO, and a .992 OPS in 40 plate appearances, he's been markedly better on the road. The 28-year-old owns a .361 average, six home runs, a .528 ISO, and a 1.367 OPS in 46 road plate appearances.

What’s more, the Athletics entered Wednesday with the sixth-fewest runs scored in the league and tied for the seventh-lowest on-base percentage. Put the 28-year-old in even a middle-of-the-pack lineup and his fantasy fortunes will improve considerably. The other key difference here is that Rooker has essentially been elite across the board in whatever metric you want to pick. Well, except for his strikeout rate and whiff rate.

Otherwise, Rooker ranks in the 98^th percentile or better in xwOBA, xSLG, and barrel rate with a walk rate that sits in the 93^rd percentile, making him the ideal addition for either standard scoring leagues or leagues where on-base percentage is part of the scoring. There are also 82^nd percentile rankings in both hard-hit rate and chase rate.

He’s likely been added off waivers in your league weeks ago, but if there’s a chance the fantasy manager thinks this is more of a fluke and not a breakout season from the 28-year-old, now is the perfect time to try working out a deal.

The A’s slugger, based on his current metrics, looks like a hitter who'll be a top-25 fantasy player for the rest of the season, especially if Oakland trades him to a team with a much more fantasy-friendly environment. If the fantasy manager in your league is open to moving Rooker for a return that checks in below that of a top 25 or top 50 player from a trade value standpoint, jump at the chance to make the move.

Overvalued Players To Trade Away

Bryce Elder, Atlanta Braves

Elder has provided both Atlanta and fantasy managers with some quality innings so far, pitching to a 1.75 ERA and a 3.59 FIP in 36 frames. The right-hander has added 32 strikeouts compared to just nine walks allowed in the process while winning three of his six starts. Just at surface value, his 1.75 ERA probably isn’t sustainable. And while his 3.59 FIP is still a decidedly solid number, now might just be the time to try and trade Elder.

The 23-year-old hasn’t been able to generate a ton of weak contact, with a 48.5% hard-hit rate so far. That in itself would be a cause for concern, but it's particularly alarming considering Elder’s pitch arsenal is fronted by an 89.1 MPH (on average) sinker with a 38.1% usage rate. Elsewhere, the Atlanta starter’s fourth-most utilized pitch is a four-seamer that sports a 12.2 usage rate and averages 90.3 MPH.

Generally speaking, starters with lower velocity fastballs that get crushed are players to avoid in fantasy, and opposing batters have crushed Elder’s sinker and four-seamer so far.

• Bryce Elder’s Sinker In 2023: 38.1% usage rate, .295 average, .308 xBA, .361 wOBA, .380 xwOBA, 19.8% whiff rate
• Bryce Elder’s Four-Seamer In 2023: 12.2% usage rate, .333 average, .371 xBA, .490 wOBA, .539 xwOBA, 31.4% whiff rate

While Elder’s slider and changeup have both been reasonably effective so far – opposing batters have posted xwOBA metrics of .231 and .289 respectively against the two pitches – his significant fastball usage seems unsustainable if batters are going to keep teeing off on the sinker and four-seamer.

Entering play Wednesday, Elder ranked in the 15^th percentile or lower in hard-hit rate (14^th), average exit velocity (ninth), fastball velocity (eighth), and fastball spin rate (third). The former fifth-round pick's lack of walks – he’s posted a 6.3% walk rate and has allowed 2.25 walks per nine innings – makes him a playable fantasy option. So too does a spot in an Atlanta rotation that should provide him with some pitcher-win opportunities.

However, if you can move him for a similarly productive starting pitcher without the significant regression concerns, now’s the time to make a trade.

Geraldo Perdomo, Arizona Diamondbacks

Perdomo is off to a strong start for the Arizona Diamondbacks, hitting .391 with a .458 on-base percentage, two home runs, and a stolen base in 75 plate appearances for the National League West club. He’s doing a number of things right at the plate, particularly from a plate discipline standpoint, with just an 18.9% chase rate, an 18.9% whiff rate, and an 86.9% zone contact rate. For leagues where on-base percentage is part of the scoring, he’s also walking 9.3% of the time.

Those are all encouraging metrics. So too is an 18.7% strikeout rate. What’s not as encouraging is Perdomo’s lack of hard contact. While he’s making plenty of contact, it’s generally not the preferable type of loud contact. Perdomo is sporting a 15.1% hard-hit rate and just a .310 xwOBAcon. It’s not exactly an ideal set of stats, especially when paired with the infielder’s .391 average and sky-high .479 BABIP.

In other words, expect some serious regression at the plate from a production standpoint. That’s especially the case considering there’s also a sizeable gap between the 23-year-old’s .460 wOBA – which is decidedly very good – and his .293 xwOBA, which isn’t as stellar, ranking in the 24^th percentile in the league.

There’s also the fact that much of Perdomo’s production has come via fastballs. Fastballs have represented 64% of the pitches the infielder has seen this season, and he’s hitting .347 against them with a .394 wOBA. However, the expected stats tell a much different story, most notably the infielder's .224 xBA and a .261 xwOBA against fastballs.

Considering he’s eligible at third base (as well as shortstop) in Yahoo leagues, he makes for an ideal trade candidate considering the relatively shallow fantasy depth at the hot corner league-wide.

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