Fantasy Baseball Overvalued and Undervalued – Cardinals Flying High in 2026

As we approach five months into the fantasy baseball season, we can now solidly say who is overvalued and undervalued based on the cost to acquire their services in drafts or auctions this spring. Some fantasy baseball player performances have exceeded expectations, while others have fallen behind. Time is running out to change their season, and they have proved who they are.

Value is an ever-changing target, of course, but we do have a snapshot in time to look at how we valued them in our drafts this spring. With about 40 games left for each team this season, it’s a good time to look at who is performing how we hoped, and who is falling behind.

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This weekly piece will look at the past couple of weeks of fantasy baseball performances to see who should be considered overvalued and undervalued going forward. When necessary, I will reference the Fantrax top 400 rotisserie rankings for the 2026 fantasy baseball season.

Fantasy Baseball’s Most Undervalued Players

(Stats are up to date as of August 17)

JJ Wetherholt (2B – STL)

The 23-year-old rookie second baseman for the St. Louis Cardinals has quickly become one of the best values in fantasy baseball, no matter where they were taken in drafts this past spring. Through his first 120 games this season, Wetherholt has posted a .724 OPS with 16 home runs, 46 RBI, 13 stolen bases, and 81 runs while showing the advanced plate discipline that made him one of baseball’s premier prospects. His 11.4% walk rate is outstanding for a young rookie, and his .347 xwOBA suggests his strong start is fully supported.

What makes Wetherholt particularly attractive in fantasy formats is his disciplined approach at the plate, especially for a young age. He combines a 43.6% hard-hit rate with strong on-base skills. In the minors during 2025, he posted a .306/.421/.510 line with 17 home runs and 23 stolen bases, showing he has the 20-homer, 20-steal upside that could come as soon as 2026 or 2027 at the latest. Wetherholt’s under-the-hood metrics tell us he should be treated as a no-doubt-about-it fantasy starter, and teams have finally caught on now that he is 100% rostered in Fantrax leagues.

Riley O’Brien (RP – STL)

Here are the pitching stats for two pitchers through August 17 of the 2026 season:

Pitcher A – 55 innings, three wins, 31 saves, 77 strikeouts, 2.29 ERA, 1.11 WHIP

Pitcher B – 50.2 innings, three wins, 31 saves, 52 strikeouts, 0.96 ERA, 1.09 WHIP

Pitcher A is Cade Smith, one of the best relief pitchers in 2026 and one of the most reliable sources of saves. Pitcher B is Riley O’Brien. Apparently it’s Cardinals’ day in the Undervalued part of the column.

The strikeouts are going to favor Smith here, but saves, wins, and ratios are all essentially the same. Smith has allowed fewer runs, but he also was drafted about 10 rounds higher. Considering the number of innings pitched and saves for each, there is a strong argument to make that Riley O’Brien has been as valuable as Cade Smith.

Varland has given up two total earned runs since June 22 and has multiple instances where he struck out the side over the last three weeks. He has seven saves in the last month and has actually allowed only one hit since July 20.

Next season, the ADP between these two closers is going to be much closer considering how competitive the Cardinals have been and how reliable O’Brien has proven to be. He has been one of the best relievers for more than two months.

Fantasy Baseball’s Most Overvalued Players

Paul Skenes (SP – PIT)

I’ve avoided writing about Paul Skenes for a couple of months, assured that things would turn around. But based on value and spring ADP, Skenes just hasn’t paid off this season. He was one of the safest-looking picks in fantasy baseball entering 2026, routinely going in the first five picks of many drafts. However, the reigning NL Cy Young winner has been a major disappointment, posting a 3.88 ERA and 1.12 WHIP with a 9-11 record through 25 starts. His 30.0% strikeout rate remains excellent, but it is a noticeable step down from the dominance fantasy managers expected, particularly when compared with the 1.97 ERA he posted in 2025.

Skenes’ fastball velocity has fallen, with his average fastball sitting around 96.9 mph compared with nearly 100 mph at times last season (and was over 98 all season). That decline has led to a 5.79 ERA over his last nine starts, and he was recently pulled after only 65 pitches, failing to reach 97 mph with his fastball. The Pirates have said there is no injury issue, but the combination of diminished velocity, workload concerns, and opposing hitters having success against him has led to a fantasy ace delivering something equivalent to what you expect from an SP3 or SP4.

Jacob DeGrom (SP –TEX)

The end comes for everyone in baseball, even superstar pitchers like Jacob DeGrom. Jacob DeGrom’s recent decline and injury worries are particularly notable because they come after an June when he looked like his old self again. DeGrom posted an elite 3.00 ERA and 2.59 xERA over his 36 innings in June, with an 11.5 strikeouts per nine rate. July and August have been a very different story.

Over the last 30 days before his injury, he finished with a 6.30 ERA, 4.64 xERA, and a 1-3 record in 20 innings, despite an 11.25 K/9 rate. That suggests the strikeout ability remains elite, but his ability to keep men off base and prevent runs that made him such a dominant fantasy starter has disappeared as the season ground along.

DeGrom is definitely an overvalued player right now and might fall way down draft boards next season. The strikeout ceiling remains high, but managers should recognize that the dominant version from earlier years has not carried over into the second half of 2026. He is seeing his walks go up, his hard-hit rate allowed is the second-highest of his career (12 points above his career number), and his barrel rate allowed is close to 9%, while his career number is 6.3%.