The newest tool in our belt for evaluating prospects is ProspectSavant.com, which displays statcast data for the minor leagues similar to MLB’s Baseball Savant. Those systems aren’t in every minor league ballpark yet, so far just AAA and 10 A-ball parks (I goofed and referred to Kemp Alderman’s AA numbers last week, they were actually high-A), but that’s still enough to be useful. It’s also worth noting that if a player has no data, they won’t show up on the site to search for.
Statline Scouting Prospect Savant
Player Pages
So far, the main way I’ve used Prospect Savant is to take a closer look at players I found on FanGraphs or heard about elsewhere. Let’s take a look at one from last week, Joe Mack
Here we get a bunch of stats displayed as “lollipops” showing the absolute value on the right, but using color-coded bars to display how good that stat is compared to all players it has data for, as a percentile. So, if we aren’t used to looking at Barrel rate, it tells us that Mack’s 10.5% is better than 76% of hitters. This also handles values where lower is better, like Chase rate, where Mack is well below average at a hair over 30%.
xStats
xwOBA is formulated using exit velocity, launch angle, and, on certain types of batted balls, Sprint Speed. This gives us a good summary of hitting value based on quality of contact. xBA and xSLG give us data-based measures of Hit Tool and Game Power
Quality of Contact Stats
EV – Average Exit Velocity, maxEV, Barrel%, and Hard-Hit% give us insight into how often a player makes quality contact, and how much juice they’re putting into the ball when they do. If you’re familiar with these numbers for MLB, you know we want to see average EVs of at least 90, and max of 110 to definitively say a guy has above average power. Mack falls a bit short of that at 105, but his Barrel and HH% show us why his average EV is still good. We might think of this as more of a “doubles power” profile in traditional terms, but it’s still a small sample, and we can see in both his scouting grades and traditional stats that he’s getting the ball over the fence plenty. Even without top-end power, these numbers show us that he’s doing plenty of damage.
Contact and Plate Discipline Stats
Z-Swing and Chase% show us how often he swings at balls in and out of the strike zone, respectively. We see that both are high, so he’s a pretty free swinger. Chase isn’t great, but we do want batters to swing at strikes. Z-Contact is an important indicator of how much good plate discipline pays off, as you have to connect with strikes to succeed. Mack’s 66% is… abysmal. 3rd percentile and a big red flag for his batting average projection. That seems at odds with his quality of contact, he doesn’t seem to be missing the balls he hits. We’ll see why later.
Whiff% and SwStr% might sound like the same thing, but there’s a subtle difference. Swinging Strike rate measures all pitches seen, while Whiff rate is just pitches swung at (the inverse of Contact%). Mack isn’t good by either measure. Finally, we have K% and BB%, which are actually pretty good despite being a free-swinger with contact issues. This suggests he A) isn’t seeing a ton of strikes and B) has a pretty good eye for the zone, but has a pretty high estimation of what he can hit. This is working at AAA, but it is the kind of profile MLB pitchers can exploit.
For a more thorough explanation on these, see this intro to plate discipline metrics by Dave Cherman on PitcherList
Lastly we have Speed metrics, which tell us Mack isn’t a burner. Not surprising for a catcher, but it tells us that the 45/40 scouting grades may be a bit generous.
Pitch Type Performance
| Pitch Type | Usage | xwOBA | xSLG |
|---|---|---|---|
| 4-Seam | 31.4% | .527 | .793 |
| Slider | 21.6% | .299 | .358 |
| Change | 20.3% | .312 | .225 |
| Splitter | 7.8% | .000 | .000 |
| Cutter | 7.8% | .703 | .267 |
| Curve | 4.6% | .696 | .000 |
| Sweeper | 3.9% | .356 | .468 |
This is where we see how Mack is able to hit balls so well while making so little contact. He is absolutely demolishing fastballs, but offspeed stuff is making him look foolish. This is another trait that MLB pitchers can pretty easily exploit, as he will face more and better breaking balls in the majors. So, if you ran out and picked up Mack last week, this throws some cold water on that, but the season is still young, we just want to keep an eye on these numbers to see if he adjusts to the higher quality pitches at a new level. And pitchers do have to throw him fastballs sometime, so he will still have his chances. The big question Mack (and most prospects) has to answer is: “Is the damage worth the whiffs?”
Leaderboards
The ProspectSavant Leaderboards offer a few added stats that aggregate some of these into a single score – Power sums up quality of contact and Discipline combines swing decision and contact metrics. PS Score and Agg are a combination of everything, with PS Score weighing stats differently to try to give an overall value estimation.
This list is mostly names we recognize, with Roman Anthony at the top, followed by Moises Ballesteros and Adael Amador. Not far behind are the likes of Nick Kurtz, Samuel Basallo, and Coby Mayo. I’m still feeling out how much to weigh these rankings, and I want to use Mayo as an example of why, because he came up last year and struck out 47.8% of the time. Now, I’m generally not one to overreact to poor performances when a player gets their first taste of a new level, especially the majors, but we tend to get excited about call-ups and expect immediate success, and I think there’s a lesson here about a profile we should expect to struggle. Here’s what Mayo did in 2024
Elite EVs and Barrel rate, but below average contact rates. Let’s take a look at another recent call-up, Nick Kurtz
Pretty similar shape, huh? What’s he done so far? Oh, 44.4% strikeout rate… Who else has this kind of profile that we think might be up this summer?
That’s Owen Cassie, Carson Williams, and Devyison De Los Santos. I’m not out on these guys by any means, but I’m tempering my short-term expectations when they debut. If you have them, don’t panic, but this might be the peak of their value. A contender would do better to flip them than expect them to be reinforcements this year. If you love them, there may be a buying opportunity when they come up. Just know that this profile is going to be streaky and will really push the “Is the damage worth the whiffs?” calculus to its limits.
Next time we return to FanGraphs to statline scout pitchers
