Casey Mize, Vlad Jr. and the craziest minor league stats ever

Tigers No. 1 pick Casey Mize -- like Blue Jays slugger Vladimir Guerrero Jr. before him -- is the latest in a series of prospects who have no business being in the league they're in. But not every amazing performance is created equal. Mark Olson/Minor League Baseball via AP

The earned run Casey Mize allowed to the Clearwater Threshers on April 9 was a bit of a cheapie. Mize got the first two outs of the second inning, then clipped the Threshers' No. 6 hitter on a two-strike cutter. That guy stole second, and the next batter blooped a two-strike fastball at the very top of the zone into center field for a single.

"Frustrating," Mize called it. "I got it in on his hands, yet he was able to poke it over second base."

That was the first earned run that Mize, the first overall pick of the Detroit Tigers in last June's draft, allowed this year, coming in his second start. He wouldn't allow another earned run until his seventh start of the season, which came Friday.

For the most part, minor league stats look a lot like major league stats. To pick some random leagues: The OPS champ in the Triple-A International League last year had a .997 OPS. Normal. The ERA title in the Double-A Eastern League went to a guy with a 3.04 ERA. Normal. A very normal 34 homers led the Single-A South Atlantic League. In theory, the only league in professional baseball where incomprehensible numbers should happen is the majors, because that's the only place where there isn't a higher league to move up to. Otherwise, it doesn't really matter which level you glance at: .300 is a good batting average, 100 is a lot of runs batted in, and good pitchers go 13-8.

Then something like Mize happens. In four starts at high-A this year, he allowed just the one frustrating run. That got him bumped up to Double-A, where he threw a no-hitter in his first start. In seven starts total this year, he has a 0.60 ERA, with 40 strikeouts and just three walks.

Every few years, in one of stateside baseball's 16 affiliated minor leagues, somebody breaks the margins. In most cases, that somebody is a superstar -- a future superstar, technically, but really already a superstar who is merely temporarily misidentified as in need of more development.

We have a lot of favorite minor league performances. Most of them tell a story of a player who has no business being in the league he's in, but the stories have subtle (or not subtle) differences. Broadly speaking, there are five types of farcical minor league stat lines:

1. The mostly meaningless lines

For example: Tim McWilliam's .451/.516/.637 line for the 1988 AZL Padres

The mostly meaningless lines tend to be by players who are older than most of their competition: McWilliam was the oldest hitter on his team, which comprised mostly teenagers. This age discrepancy doesn't invalidate what McWilliam did, any more than it invalidates Gary Redus' .462/.559/.787 for the short-season Billings Mustangs in 1978, or Jake Fox's .409/.495/.841 line for Triple-A Iowa in 2009. There were other 21-year-olds in the Arizona League that year, and none of them hit anywhere close to .451. So the batting line is still data. It's just that the fact that he was the oldest player on his team is better data, assuming (as you should) that his team is rational and not assigning players to its affiliates randomly.

(McWilliam never hit .300 again. He reached Triple-A, for two games, and was out of baseball by age 26. Redus had a successful major league career, as a roughly league-average hitter for 13 years. Fox got about 500 big league plate appearances and hit poorly.)

2. The showed-up-too-ready lines

For example: Roger Clemens' 1.33 ERA in Class A and high-A, 1983.

Clemens was the 19th overall pick in the 1983 draft, and the Red Sox had to send him somewhere. So they sent him to Single-A Winter Haven, where he struck out 36 batters and walked none across 29 innings. That got him promoted to Double-A New Britain, and in seven starts (52 innings) he allowed only eight runs. His combined line: 1.33 ERA, 95 strikeouts and 12 walks, one home run allowed, in 81 innings. The next year, when he was in the majors, where he belonged all along, he had the best FIP of any AL starter.

"Think horses, not zebras," doctors are told, and generally speaking, the advice holds for scouts and executives, too: The guy you draft 19th overall could be the greatest pitcher of all time and ready for the majors immediately, as Clemens was. As Dylan Bundy (0.00 ERA in Single-A Delmarva; 40 strikeouts and seven baserunners in 30 innings) probably was, and as Tim Lincecum (15 strikeouts per nine, 1.01 ERA across three minor league levels before his debut) certainly was. But he's almost certainly not, and you can't know otherwise until you've seen it. So first the pitcher goes out and humiliates a bunch of minor leaguers. We have little choice but to accept that wasting a few of the player's best innings in Delmarva is the cost of living uncertainly.

3. The transformed-too-abruptly lines

For example: Jim Thome's .373/.503/.754 in the Appalachian League in 1990.

Thome, a 13th-round pick, debuted with Cleveland's instructional league team in 1989. He batted 213 times and didn't homer once. He slugged .296. Jim Thome!

So he started the next season in short-season ball, an appropriate assignment, but something had changed in the offseason: He homered every 10th at-bat and walked every fifth in Burlington.

Most future stars show up to the minors too young, too undeveloped, too flawed, good enough to play well in the minors but certainly not good enough to play well in the majors. Then they make progress and move up in the minors, but progress isn't always steady. Sometimes it happens in an offseason. Andruw Jones was already one of the best prospects in baseball entering 1995, with a very Andruw Jonesian .277/.372/.512 line as an 18-year-old the year before. Then he hit .313/.419/.605 in high-A, and then .369/.432/.675 in Double-A, and then .378/.391/.822 in Triple-A -- all in the same year. Suddenly, he was the best prospect in baseball, and one of the best in history.

4. The absolutely-unrepeatable-circumstances lines

For example: Rick Ankiel's .286/.364/.638 hitting line, and 1.33 ERA pitching line, for rookie ball Johnson City in 2001.

Ankiel, at this point, had already been the No. 1 prospect in baseball; he finished second in Rookie of the Year voting and started two postseason games. But he was also only 21, a little old but not that old for rookie ball, where the average player was 20.

He had been sent down by the Cardinals to try to figure out his yips, which had caused him to walk 53 batters in his previous 32 innings (including in the postseason and Triple-A). Again, he wasn't that old, but he was just so much more advanced than anybody else in the league that year, and in 88 innings he struck out 158 -- more than 16 per nine innings -- and walked only 18. I'm not sure professional baseball has a more dominant pitching line this century than Ankiel's.

But even wilder, he also DH'd on his off days, and he was one of the best half-dozen hitters in the league, homering 10 times in 105 at-bats and edging Joe Mauer for the second-best OPS in the league. This was all an artificial setup, both entirely appropriate for the situation and perhaps never to be repeated.

5. The unfortunate-modern-service-time-rules lines

For example: Vladimir Guerrero Jr.'s .402/.449/.671 in Double-A New Hampshire in 2018.

By May of last year, it was already fashionable to wonder why Guerrero wasn't already in the majors, but of course the answer was obvious: service time shenanigans. The Blue Jays could make the coldly rational, clearly unfun calculation to keep Guerrero in the minors because (A) the big league club was going nowhere that season, no matter where Guerrero played and (B) keeping him in the minors would keep him under the club's control further into the future. This is a new kind of farcical stat line, one that has become far more common in recent years:

Kris Bryant's .355/.458/.702 in a half-season of Double-A in 2014 would probably never have existed a generation ago, because the Cubs would have moved him up three weeks into it. Same, perhaps, for George Springer's .353/.459/.647 line over a month in Triple-A in 2014, when the Astros were holding him back a few weeks to gain an extra year of free agency. Every day the Marlins' Zac Gallen spends in Triple-A -- his ERA just above 1.00, his strikeout and walk rates outrageous -- feels more artificial.

That's why we're, uh, blessed with Mize's line this year, and why he will quite possibly spend the rest of the season (and a few weeks of next) adding to it. The minor leagues are mostly a place for young players to develop -- a good purpose. Increasingly, they're a place for teams to slow their best prospects down.

A player who slugs .800 in the low minors usually doesn't belong in the low minors, and a pitcher with a 1.00 ERA in Double-A belongs on national TV, not MiLB.tv. But you can't predict baseball prospects, and some farces are inevitable. When Juan Soto unexpectedly hit .373/.486/.814 in A-ball last season, the Nationals reacted quickly, and by mid-May -- far earlier than expected -- Soto's minor league performance had earned him a spot in the majors. His original assignment to Hagerstown was a small failure, but an honest one, and it was part of the process of getting Soto where he truly belonged. Unfortunately, increasingly, the farcical minor league line is by design. If Mize dominates the minors like this all year, it won't be charming. It'll be a policy failure.

Some other extraordinary minor league lines:

  • Tony Gwynn hit .462/.490/.725 in Double-A (99 PA).

  • Howie Kendrick hit .368 in rookie ball, then .367 in A-ball, then .384 in high-A, then .342 in Double-A, then .369 in Triple-A.

  • Mariano Rivera had a 0.17 ERA -- one earned run in 52 innings -- in rookie ball. He was used as a reliever, but when he started the final game of the season, he threw a no-hitter.

  • Julio Urias had a 2.48 ERA and 11 strikeouts per nine when he was 16, pitching in the Midwest League, where the average pitcher was 22.