Sam McWilliams Blossoms As A Prospect

Low Class A righthander Sam McWilliams was the proverbial ball of clay for player development when the Diamondbacks acquired him two years ago. The 21-year-old seems to be rounding into form in the Midwest League.

With a lively, low- to mid-90s fastball, a slider and what scouts describe as a work-in-progress changeup, McWilliams has taken steps forward this season.

“I see him starting in the big leagues in a few years,” Kane County pitching coach Rich Sauveur said. “You’ve got a kid who’s throwing 95 (mph) with downhill plane, commanding his fastball, has a true slider and if he has a (changeup) that’s at least a major league average, he should be successful there.”

McWilliams had no trouble in his second go-round in the MWL. Through 17 starts, he went 9-3, 2.23 with 70 strikeouts compared to just 19 walks and just three home runs allowed.

A 2014 eighth-round pick by the Phillies out of Tennessee high school, McWilliams was shipped to the D-backs a year later in the Jeremy Hellickson trade. He says he got out of whack mechanically during his first season with his new organization. As a result, he lost velocity off his fastball and struggled with his breaking ball.

But McWilliams arrived at spring training this year looking to be more athletic in his delivery. He says it’s made a big difference. His velocity has ticked back up and his slider has become harder and sharper.

“I’m just attacking guys, being aggressive and trusting my stuff,” McWilliams said. “Me and (Sauveur) talked about it a lot last year, and we continued it this year. I like my two-seamer, and throwing it in to righties has been huge for me.”

At 6-foot-7, he was considered raw and projectable out of high school. He’s added more than 30 pounds to his frame since the draft and now weighs in around 225.

“I think I’ve grown up a little bit,” McWilliams said. “I’ve learned my body a little more, got into the weight room. That’s helped a lot. I feel better about it. I feel a lot stronger.”

The developmental focus, for now, is on his changeup. He thinks he’s made progress since switching from a circle grip to a split-change grip.

“Over the past month or so I’ve gotten a lot more comfortable with it,” he said. “I kind of think fastball and throw it like that.”