Prospect Scouting & Stats — Pitcher SL – Present

Yesterday was the start of our look at prospect pitcher individual pitch grades, as I began with the fastball. Today, let’s move on to the slider. Now, I present to you the top 8 pitchers in Slider – Present (SP) grade, as sorted first by grade, and then by FV.

Mariners prospect Sam Delaplane has the honor of being the only pitcher given a 70 grade slider. The then-24-year-old was a bit old for Double-A, but his career got a late start, as he first made his professional debut at age 22. He has been a career reliever, so really the only hope here is eventually closerdom, or some value in middle relief in an AL-Only league. He has posted some spectacular strikeout rates in the minors, all over 30% at every stop, and as high as 48.4%. Those strikeouts have been supported by elite SwStk% marks, mostly over 20%. Since his fastball grades at a 60, it doesn’t seem like he’s just a minor league success story whose stuff won’t fool Major League hitters. With the entire Mariners bullpen a mess, this is as strong a darkhorse saves candidate in the near future as there is.

There’s Jesus Luzardo again, who appeared on yesterday’s fastball leaderboard as well. Is it really fair for a pitcher to own a 70 grade fastball and a 65 grade slider? I do wonder why his minor league strikeout rates haven’t been higher though.

So Nate Pearson has an 80 grade fastball that maxes out over 100 MPH, and yet his slider grades out at 60 too?! Good luck to hitters! But like Luzardo, I’m baffled how with these pitch grades, his strikeout rate hasn’t been even higher in the minors.

I think Dustin May is a better real life prospect than fantasy one because of his only decent strikeout rates in the minors. That said, with excellent control and a strong ground ball tilt, he’s still rather interesting. From an underlying metrics perspective, he appears similar to Marcus Stroman, with the high grounder rate, good control, and merely average, at best, strikeout rate. That’s usable, but perhaps overhyped in fantasy circles.

The first overall pick in the 2018 draft, Casey Mize is now our 16th best prospect. While his strikeout rates haven’t been that impressive, his AA SwStk% does suggest better strikeout ability than the rate he actually posted. Right now though, I don’t think he’s worth thinking of as one of the best pitching prospects in baseball as the skills just haven’t been good enough yet to earn that honor.

A.J. Puk missed the entire 2018 season after undergoing TJ surgery, but has seemingly made a full recovery given his small sample minor league skills in 2019. He even made 10 appearances with the Athletics and averaged 97 MPH with his fastball, so his velocity appears all the way back, which is a great sign. He threw that 60 grade slider about 25% of the time and it generated a strong, albeit not elite, 20% SwStk%, but the sample was pretty small. Assuming his shoulder is healthy, he’s a much better target than his teammate Luzardo as he’ll come much cheaper and has a reasonable chance of performing better.

It’s hard to find a worse debut than Mitch Keller suffered…at least on the surface. He posted a gruesome 7.13 ERA in 48 innings, which is primarily driven by an insane .475 BABIP, which kept his LOB down at just 59.6%. Keller’s strikeout rate has been up and down in the minors, from the low to high 20% range, so it’s hard to get a sense of what he’s capable of in the Majors. He threw his 60 grade slider about 21% of the time, and it was darn elite, generating a fantastic 26.8% SwStk%. It also induced grounders 56% of the time, so it was truly an elite pitch. As long as he has better batted ball luck, he should deliver solid profit for his owners and his ERA could drop over three full runs.

Last, we find another repeat from our fastball list, Brusdar Graterol. He’s armed with a big fastball and excellent slider, plus he generates ground balls. I would love to see him as a starter sometime in the future.