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Dirty Thirty-Five: Prospect #26 Alvaro Seijas

Updated: Dec 16, 2018

Prospect #26: RHP Alvaro Seijas

Previously Ranked 28th in preseason and ranked 30th at July reranking

Peoria Chiefs

International Signing in 2015


The Stats


The stats are rough for Seijas. The teenager has had a rough go of it during his first taste of full season baseball. I almost dropped Seijas off of the list entirely, but then I remembered to keep everything in context. See, Seijas' rotation and international signing mate Johan Oviedo has had a brutal run for Peoria. I was always higher on Oviedo because of his size and because I believed he could be over-powering. However, watching Oviedo's command fail him this season has caused pause in any type of positive evaluation. Now, with that in mind, what Seijas has done at Peoria doesn't look so bad. His command isn't completely in the toilet, although his emotions do tend to get the best of him when he struggles to find the zone. He's struggling, but his velocity is still solid, sitting in the low-mid low 90's, and he's still a teenager pitching against advanced hitters.

So, what I'm getting at is, Seijas stays on the list because we don't completely give up on teen aged prospects that were once highly touted until they give us a reason to. Oviedo and his extreme command issue is a major concern, so off of the list he goes for now. Seijas stays because the promise is still there. With a good fastball and a breaking pitch that shows signs of being very good, Seijas stays on the list. He falls down the list because it's been rough this year. The second half of the season is going to be big for Seijas. It's going to be a hot summer and that always bodes well for the teen aged international signings.


  • Seijas is only 19-years-old and pitching at a full season affiliate.

  • He was considered the best pitcher in his International Signing Class.

  • He throws a good curve ball that, while inconsistent, has plus-potential.

  • His fastball has tremendous life to go along with it's low-mid 90's velocity.

  • He's athletic and has gained weight to fill out his frame.

  • At 6'2" and right around 180 pounds, Seijas' frame will hold up.

  • While his stats aren't pretty and the line tells you that he's trending in the wrong direction, I do believe that I've seen some improvement in how he's attacking hitters as well as the sharpness in his breaking pitch.

  • At 19 and already at a full season level, Seijas has plenty of time to sort it out and get better. All of the tools are there.

  • Seijas has been better of late while eliminating some of the high walk totals that he displayed in early season starts.


  • All of his stats are trending in the wrong direction.

  • While it seemed like Seijas was doing a good job of inducing ground balls last season, that trend hasn't continue this season.

  • The concern with Seijas is that he was always going to be a bullpen arm. With his current production, that'd be the most likely outcome.

  • The development of a third pitch to go along with his curve ball and fastball has stunted. It's more inconsistent than his curve ball.

  • Seijas has put on weight to help fill out his frame, but he'd do well to turn some of that weight into muscle. He's muscular now, but without definition and it doesn't all seem like the "right kind of weight."

  • Again, he's extremely young for the level, but a sub six K/9 and a 3.90 BB/9 is alarming and unsustainable in any capacity. He might be best suited for a demotion to State College to work some stuff out.

  • He's gotten better about it as the season has progressed, but there are times when his lack of command takes over his emotions. In these moments, he works quicker in an effort to correct the ball-throwing and it usually throws off his mechanics. When this happens, he usually tips his curve ball heavily.

  • Seijas has cleaned up his mechanics but there are still some that worry about the health of his arm because of his timing, motion, arm angle, and mechanics.


Just like with the other 20-year -old-and-younger on this list, it's probably not fair to make a comparison for Seijas. If he ends up having to be a bullpen arm and he maxes out, then you're probably looking at his 5% ultimate ceiling as something similar to Sergio Romo, but with a curve instead of a slider. Right now, his most likely ultimate ceiling is probably something similar to Fernando Salas if he stays in the bullpen. It's important to remember that you always hold off until the very last minute to convert a starter to to relief. Starting is still his ultimate potential and ceiling. The teenager is going to need a lot of work to reach that. He has time and the tools, though, and I wouldn't bet against him.

Thanks to Fangraphs for being stat-tacular!

Thanks For Reading!!

Kyle Reis

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