The Nats had a lot of prospects take meaningful strides in 2026, but the one I want to talk about today is Miguel Sime. When the Nats took Sime in the 4th round of the 2025 draft, he was a raw but electric prospect with a massive fastball, but not much else. There is still rawness in his game, but Sime took big steps in the right direction this year.
The development of Sime’s slider is the biggest story of this season. Heading into the year, Sime had a curveball and changeup to go with his triple
digit heater. Both pitches had promise, but neither were refined yet. In the offseason and during Spring Training, Sime worked hard to find a slider grip that worked for him. He talked about this in an interview last month.
Once he found the right grip, the pitch came naturally to him. The slider became Sime’s go to weapon, even throwing it more than his fastball at times. Sime’s slider has deceptive downward movement that makes it difficult to pick up. Hitters often think the slider is coming and by the time they realize their mistake it is too late.
The development of the slider gives Sime two elite pitches. His body type, pitch mix, velocity and control woes remind me a lot of Jarlin Susana. Like Susana, Sime generates a ton of swing and misses. For the season, his strikeout rate was 41.3%, or 16.18 K/9. Even as he got aggressively assigned to High-A, that strikeout rate remained around 40%.
That mid-season promotion told me a lot about how much the Nats believe in Sime as both a pitcher and competitor. They easily could have left him in Low-A to develop for the rest of the year. However, the organization wanted to challenge him and Sime responded well.
His numbers were actually much better despite facing better opposition. In Low-A, Sime struck out over 45% of hitters, but posted a 4.44 ERA due to a 21% walk rate and some bad luck. Once he got to Wilmington, Sime posted a 2.15 ERA with 76 strikeouts in 46 innings. His walk rate was still an alarming 19.9%, but it did not matter because opponents hit under .150 against him.
Obviously, control is the biggest thing Sime needs to work on. We knew his control was not pinpoint heading into pro ball, and we saw that play out. However, his stuff might be even better than expected. Sime’s fastball shape is very good and as mentioned, the slider has become a lethal weapon. At the Futures Game, Sime’s raw stuff might have been the best of any pitcher.
Between the Futures Game outing and his Spring Breakout appearance, the stuff models loved his pitches when there was Statcast data. He has velocity, movement, deception and several different nasty offerings. At 19 years old, there is still plenty of time for the control to come around.
However, that lack of present control does give him a lot of relief risk. If I had to bet right now, I do think the bullpen is Sime’s ultimate home. That is no sure thing though, and the Nats will and should give him every opportunity to prove he can start. With how young he is, we have plenty of time.
Despite his youth, there is a chance that Sime starts next season in AA as a teenager. He showed that his stuff can overwhelm High-A hitters. While he has walk problems, they have not mattered that much yet. In Double-A, those control issues are likely to hurt him more and force him to adapt.
Overall, Sime is a high upside arm with triple digit velocity and a nasty slider. His huge physical presence gives him an intimidating look on the mound. All of these things scream future closer, but his ultimate home is still to be determined.
If the control trends in the right direction, Sime could be one of the top pitching prospects in baseball. Even with shaky control, he has loud enough stuff to make him a fairly safe bet to pitch in the big leagues for a long time. Sime’s first year in pro ball was a resounding success. Now I am excited to see what he can do in year two.
