Arizona Fall League Roster Breakdown: Mesa Solar Sox

As Minor League Baseball wraps up, it is time to turn our attention to the Arizona Fall League. All Single-A and High-A affiliates are done, and Double-A playoffs are in full swing. While Triple-A is still in the regular season, it wraps up on Sunday. So as the season winds down, my mind is already in Arizona.

I will be out in the desert the second week of the AFL season to cover the league and the players there. So now is the time to break down each team’s roster and to give thoughts on players who could see their stock increase in the prospect world.

We will go team by team, alphabetically. So today, we start with Mesa. The team is comprised of prospects from the Athletics, Chicago Cubs, Miami Marlins, New York Yankees, and Tampa Bay Rays.

Mesa Solar Sox Roster Breakdown

Pitchers

Best Arm

Bryce Cunningham was off to an incredible start to the 2025 season after being selected in the second round of the 2024 MLB Draft. He went down with an injury in early June and missed over two months, pitching just 6.2 innings after returning. For the season, Cunningham had a 2.82 ERA in 54.1 innings, but 11 of his 17 earned runs allowed were over two starts.

Leading with a four-seam fastball, Cunningham creates strong carry with over 19 inches of IVB and 10 inches of horizontal movement from a six-foot release height. It makes a relatively flat VAA, considering his release height, and it gets up 97-98 mph and works in the mid-90s over longer starts.

Cunningham’s new cutter, which sits around 90 mph, is a strong pitch that he uses often. He still used his slider, which sat in the mid-to-upper 80s. The changeup might be Cunningham’s best pitch, sitting in the 88-91 mph range with carry and an average of 20 inches of horizontal movement.

It will be interesting to see what kind of innings limit Cunningham is on in Arizona. Hopefully, at this point, there is none. But, after returning on August 13, Cunningham made four starts and did not complete three innings. The arm talent is there for Cunningham to be one of the better arms in Arizona, assuming he throws enough innings.

Arm Who Could Increase Stock

Karson Milbrandt was injured this spring and got a delayed start to the season due to fluid buildup in his arm. But as the season went on, Milbrandt got better and better, finishing with a 2.90 ERA over his final 18 starts. Something clicked in July, though, as Milbrandt saw the strikeout rate jump to 35 percent over his final nine starts.

A former over-slot third-rounder in 2022, command has held back what is a deep arsenal of pitches for Milbrandt. If it does not come together, Milbrandt has the stuff to pitch in a major league bullpen, but as a younger 21-year-old, there is still hope that Milbrandt can be a starter.

The fastball has ticked up this year, and after working in the 93-95 mph range last year, Milbrandt sat 95 mph this season. He creates a good ride on the pitch, averaging 18-19 inches of IVB from a 5’8” release height while also creating good arm-side movement.

Milbrandt used to throw one slider in 2024, but now throws a cutter in the upper-80s with 3-4 inches of glove-side movement and also a sweeper that worked around 83 mph with 10-14 inches of sweep. Milbrandt can also dial it back near 80 mph with a two-plane curveball and even has a changeup that he throws sparingly.

This is a good arm that has made huge progress this year. Get in now.

Sleeper Arm

Aiden May missed a large portion of the 2025 season due to having arthroscopic elbow surgery in late March. He previously had Tommy John in 2020. He was slowly built up upon his return in July, but ended the year on a high note, tossing 5.1 no-hit innings with seven strikeouts.

May leads with a fastball around 94 mph and tops near 98 mph. It has a sinker from a 5’3” release height with heavy horizontal run, averaging over 13 inches this season. It is more of a ground ball pitch than a swing and miss offering, but that is where the changeup and slider come in.

The slider is his most used secondary, sitting in the low-80s with a ton of sweeping action. With good depth, May creates 15 inches of sweeping action regularly on the pitch and is his primary whiff pitch.

May’s changeup and cutter work in a similar velocity band in the upper-80s. The cutter is an effective pitch to keep the ball on the ground, but the changeup still is a work in progress.

Hitters

Best Bat

I struggled with this one. I could not pick out who I think is best bat will be in this lineup, but the player I think will have the best fall league is Tommy White. In a weird shift in his profile, White really cleaned up his approach and contact skills this year, but the power was not fully there, especially after he was promoted to Double-A.

In 395 plate appearances, White blasted 12 home runs and slashed .275/.334/.439 between both levels, but he hit just one home run in 113 Double-A plate appearances. The impressive thing of note is that we saw White run an 82 percent contact rate this year after having a mark at 71 percent last season.

Chase and approach were also huge issues at LSU and in his pro debut, but we saw White make strides in regard to chase rate. Ground balls have limited White significantly, as he put over half his batted balls on the ground, and something seemed to change with his timing in Double-A. After pulling 43 percent of batted balls and going to the opposite field 28 percent of the time in High-A, White went oppo 51 percent of the time in Double-A.

I could see the environment in Arizona being conducive to a big performance for White, and he could certainly use it. Put Tommy White on your AFL fantasy baseball rosters.

Bat Who Could Increase Stock

Aidan Smith was one of the buzziest names entering 2025 in public prospect circles. It seemed to me people were just trying to stamp that they were the highest on him, as I saw him in some top 20s of overall prospect rankings. I was a fan of Aidan Smith when he was drafted and in FYPDs, but after the offseason buzz and my early live looks at him in 2025, he took a tumble for me.

Through the end of May, I saw Smith show major whiffs against fastballs up in the zone and also struggling with breaking balls down and away. In those 169 plate appearances, Smith was striking out 32.5 percent of the time and had nearly identical on-base and slugging percentages (.349/.350). Smith had hit just three home runs and added four doubles.

An .854 OPS in June saw the strikeout rate drop to 31 percent, but the struggles picked back up in July. But something clicked for Smith in August, and over his final 25 games, he blasted four home runs and stole 12 bases while seeing the strikeout rate drop to 27 percent. Smith hit .280 and had a 133 wRC+.

Ending the season on a high note, Smith should have some confidence rolling into Arizona. The ball moves less there, and Smith has some of the better launch angles in the minors. He could wind up putting up good power numbers, and he is sure to steal bases. The athlete is there, and this could be the resurgence that Smith needs before a big 2026.

Sleeper Bat

Fenwick Trimble put together a good season between High-A and Double-A in 2025 despite missing nearly two months with a hamstring injury. I liked Trimble a lot coming out of college in 2024, largely thanks to a friend who worked with him at James Madison. Trimble was selected in the fourth round and struggled with his assignment to Single-A Jupiter.

Trimble was great to begin 2025 in High-A before the injury and even better after coming back in Double-A. While he did hit just seven home runs in 356 trips to the plate, Trimble was successful on 31 of 35 stolen base attempts. He showed an impressive approach and slashed .253/.372/.402.

Ground balls can be a bit of an issue at times, but Trimble made huge strides in pulling the ball in the air upon his promotion to Double-A. The contact rates are above-average, and the approach is sound. Trimble might not put up flashy numbers, but I think he is going to be a solid hitter in the Fall League.