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Chris Clegg's dynasty fantasy baseball buy lows, sell highs, and MLB news for Week 15 (2025). Notable prospects debuts and dynasty risers/fallers including Cam Smith and Andrew Abbott.
Welcome back, RotoBallers, to my dynasty fantasy baseball risers, fallers, and buys/sells for Week 15 of the 2025 MLB season. As June comes to a close, sample sizes have begun to stabilize, and there is less noise in the samples. Prospects are getting the call to majors, and there is plenty to discuss.
Today's dynasty article will look at recent prospect call-ups like Colson Montgomery, Colby Thomas, and Anthony Seigler, along with several other dynasty-related news items. This bi-weekly series will examine various prospects and dynasty news and discuss fantasy implications. If you enjoy dynasty fantasy baseball, you know it is a fast-paced game. Keeping up with current events can help you stay ahead of your league mates.
Call-ups, trends, and buying and selling players are all just small pieces to help you stay ahead. So, that's what we will do in this article each week: break down everything you need to know to be successful in dynasty. At the end of the day, we all want to build a dynasty team that sustains and lasts for the long haul. I am here to help you do so. So, what do you need to know for dynasty leagues in Week 15 of the 2025 season? Let's dive in.
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Recent MLB Prospect Call-Ups
Colby Thomas got the call from the Athletics after slashing an impressive .297/.365/.542 in Triple-A. This followed a 2024 season in which Thomas led the minors in extra-base hits by a wide margin, slashing .277/.342/.563 with 31 home runs and 15 stolen bases. Unfortunately, Thomas is working as a pinch hitter most days, which does not make a ton of sense to pull a top prospect from everyday playing time.
There is legit power in the profile, as Thomas has a 105 mph 90th percentile exit velocity. While that number is down a few ticks from last year, Thomas has topped out at 116 mph this year. His barrel rate has risen all year, now sitting at 10 percent, as the ground-ball rate has trended downward.
Some of my questions about the profile have been answered. Last year, upon his promotion to Triple-A, his contact rates faltered significantly. But so far this year, Thomas has seen a seven percentage point jump in in-zone contact, and the overall contact rate is up three percentage points. The chase rate of 34 percent is still higher than I would like to see, and I still worry about Thomas’ ability to hit good fastballs.
For the time being, Thomas should not be rostered in redraft leagues.
Colson Montgomery got the call to join the White Sox and has been quite hot. After going hitless in his debut, Montgomery had a three-hit night in his second game, which included a triple and a two-hit performance on Sunday. I believe Montgomery is a great buy for fantasy players in both redraft and dynasty at this point, given some struggles that may not be as reflective under the hood.
Montgomery was bad in Triple-A to start the season. Before hitting the development list, Montgomery was striking out in 42 percent of plate appearances and had a slash line of .149/.223/.255 in 103 trips to the plate. While at the White Sox complex in Camelback Ranch, he had a mental and mechanical reset. He did not return perfectly, but there were major improvements despite playing through an injury in May.
Under the hood, the power has looked good all year. Montgomery has a 115.3 mph max exit velocity and a 90th percentile exit velocity of 108 mph. Surprisingly, the season-long zone contact is north of 85 percent, and the chase rate is just shy of 30 percent for the season.
The strikeouts are still an issue, but Montgomery is showing positive signs, which is good for the former top White Sox prospect. He is in for a big bounceback. I am in.
CATCH OF THE SUMMER⁉️ #SCTop10
COLSON MONTGOMERY, HOW DO YOU DO‼️
(via @MLB)pic.twitter.com/jICxY3tD4y
— SportsCenter (@SportsCenter) July 5, 2025
Anthony Seigler's long journey in professional baseball has now seen him join the Brewers roster. Seigler has been in the minors since 2018 but has some pedigree as a former first-round pick. Selected by the Yankees out of Cartersville High School, Seigler received a $2.8 million bonus. He joined the Brewers organization this offseason and looks like a different player.
Seigler is hitting, and that has continued all season. He got on base in 55 of his 62 minor league games before earning the call to the majors. From May forward, Seigler slashed an impressive .315/.438/.510 with as many walks as strikeouts. For the season, Seigler is slashing .277/.416/.465 with seven home runs and 20 stolen bases.
As you might expect from the high OBP, Seigler rarely chases pitches out of the zone, having an O-swing rate of 19 percent. The contact is good, as Siegler connects on 78 percent of swings overall and 85 percent in the zone.
While he may not be a huge source of power, Seigler consistently hits the ball hard, with a 45 percent hard-hit rate and a 91.6 mph average exit velocity. His versatility is highly attractive for the Brewers, as Seigler can catch or play in the infield. While he may not play every day in a Brewers uniform, he stands a good chance of hitting his way into a bigger role. The versatility only helps.
Fantasy Baseball Dynasty Trends: Second Half Regression?
I tread carefully with expected stats, but they are always interesting to look at regarding a player and if regression could be coming. Regression could be positive or negative, so it's not always a bad thing. I examined some players with large differences in their wOBA and xwOBAs to see who might be solid buys for the second half and who could be a good sell.
For reference, the league average wOBA is .314, and xwOBA is .326. While some players could hypothetically regress, they could still be well above average.
Negative Regression Candidates
| Player | wOBA | xwOBA | Delta |
| Jacob Wilson | 0.369 | 0.311 | -0.058 |
| Alex Bregman | 0.402 | 0.359 | -0.043 |
| TJ Friedl | 0.345 | 0.307 | -0.038 |
| Jose Altuve | 0.339 | 0.302 | -0.037 |
| Cal Raleigh | 0.422 | 0.388 | -0.034 |
| Luis Arraez | 0.317 | 0.286 | -0.031 |
Positive Regression Candidates
| Player | wOBA | xwOBA | Delta |
| Andrew Vaughn | 0.232 | 0.321 | 0.089 |
| Juan Soto | 0.388 | 0.457 | 0.069 |
| Corey Seager | 0.341 | 0.41 | 0.069 |
| Bryan Reynolds | 0.295 | 0.36 | 0.065 |
| Ben Rice | 0.344 | 0.408 | 0.064 |
| Luis Garcia Jr. | 0.309 | 0.367 | 0.058 |
Fantasy Baseball Dynasty Buys
Ryan Johnson has quickly become a dynasty buy. Remember the name? The Angels shocked the world, well, sort of, by putting Johnson on the Opening Day roster without throwing a pitch in the minors, but things did not go well. In 14.2 relief innings, Johnson posted a 7.36 ERA and a 1.98 WHIP.
Johnson has been a force as a starter in High-A and has now completed at least seven innings in each of his last four starts. On Saturday, Johnson was nearly flawless. He threw a complete game and allowed just one hit and zero walks while striking out 12 batters. He struck out 12 batters and generated an incredible 25 whiffs.
Johnson has a deep arsenal of pitches and has worked on his pitch mix in the minors. Being in High-A is probably not much of a challenge for Johnson after facing MLB hitters for over a month. A promotion to Double-A Rocket City could be in order soon. He now looks like a potential solid starting pitcher, and it would not be shocking if next year he were back in the Angels rotation. He should cost you nothing right now.
Ryan Johnson ONE-HITTER
9 IP | 1 H | 0 R | 0 ER | 0 BB | 12 K
102 pitches pic.twitter.com/UD31Vsxg67
— AngelsMiLB (@AngelsMiLB) July 6, 2025
We are going to feature two buys in today's article because I have become very infatuated with Jose Soriano, also of the Angels. When you talk about innings eaters, Soriano fits the bill. Up to 104 innings in 18 starts, Soriano has completed six or more innings in 10 of his 18 starts.
The results have been pretty strong as well, and while Soriano has a 3.72 ERA, several of the other ERA indicators are lower, including a 3.25 FIP and a 3.42 xFIP. Sure, Soriano does not miss a ton of bats and has just a 20.5 percent strikeout rate this year, but the ground-ball rates are absurd. Soriano has induced a 66 percent ground-ball rate this season and has allowed just a 16 percent fly-ball rate.
Soriano uses his sinker 50 percent of the time, but runs it up to 97 mph on average. It is the ground-ball-inducing machine. There is potential for more whiffs, though, as Soriano has both his slider and curveball have whiff rates north of 43 percent. The splitter also has a 37 percent whiff rate.
It does not seem like there is much buzz around Soriano, but he is a very solid dynasty buy for me. So much so that I put him in my top 150 dynasty rankings. I would buy high on Soriano right now.
José Soriano, Wicked 86mph Knuckle Curve. 🤢
5th K pic.twitter.com/UnuaQAeSxA
— Rob Friedman (@PitchingNinja) July 4, 2025
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