What to Make of Mookie Betts

Following a stupid .451/.491/.804 performance in the Grapefruit League, the hype surrounding Red Sox outfielder Mookie Betts is through the roof. Scouts are all but penciling him into July’s All-Star lineup, and some of Betts’s peers have even gone as far as to compare him to Andrew McCutchen. And wouldn’t you know it, Betts opened the 2015 season by going 2-4 with a homer and a walk on opening day. Mookie-mania is upon us.

Here at FanGraphs, we’ve been on the Betts bandwagon for a while. Carson Cistulli’s been tracking Betts since July 2013, when he made his first appearance on one of his fringe five lists. An undersized 5th round draft pick with excellent stats, Betts was exactly the type of prospect who endears himself to prospect enthusiasts whose heads are buried in spreadsheets. At that point, Betts was merely a little-known A-Baller with an unusual name.

But last year, Betts took his act to Double-A, and kept right on hitting. He put up a 177 wRC+ in two months in Double-A, and followed it up with a 158 mark in Triple-A. The 5-9 second baseman with the funny name was starting to look like a bona fide prospect, and it was happening in a hurry.

Betts wasn’t supposed to be a part of the Red Sox plans in 2014, but he hit so well in the minors that they pretty much had no choice but to call him up. Players who hit .346/.431/.529 in the minors have no business being in the minors. Although he had only minimal experience in the outfield, it was clear that his bat could help the Red Sox right away.

Betts acquitted himself well in his first taste of big league action. Defensively, he split time between second base, center field and right field. However, he did most of his damage at the plate, where he hit an impressive .291/.368/.444. All told, he was worth nearly 2 WAR in just 52 big league games.

Although he has barley 200 big league plate appearances to his name, the projection systems are sold on Betts. Both Steamer and ZiPS anticipate wRC+s significantly better than average for the 22-year-old. Our pre-season depth charts — which incorporate both Steamer and ZiPS — project Betts for a respectable 3.4 WAR. Going by the projections, he’s already a better player than the likes of Hanley Ramirez, Ryan Braun and Adrian Gonzalez.

KATOH — my prospect projection system — is also crazy high on the Red Sox center fielder. It forecasts him for a remarkable 21.6 WAR through age-28, or an average of just over 3 WAR per year over the next seven years. His is the highest projection for any player who had at least 200 minor league plate appearances last year. Of the 331 big league hitters who were 28 or older last year, only 29 surpassed the 21.6 WAR through age-28 that my system forecasts for Betts.

Projections aren’t perfect, of course. They’re merely our best — yet still flawed — attempts at simulating the complex world around us. But still, those flawed attempts think Betts is destined for very good things. That has to be worth something.

Given his minor league numbers, it’s easy to see why a stats-based projection system would be all over Betts. He walked more than he struck out at four of his five minor league stops, and — unlike most hitters who accomplish this feat — hit for a respectable amount of power. He also demonstrated exceptional ability on the base paths. On a per 600 plate appearance basis, he stole 43 bases in 51 attempts in the minor leagues.

Although he was a 21-year-old facing pitchers much older than he was, Betts was above-average across the board. Simply put, minor league seasons like that don’t happen all that often. And when they do, the players behind those seasons often go on to do very good things in the majors.

Let’s look at some comps. Below, you’ll find a collection of comps for Betts. Each of these players played in Double-A or Triple-A at age-20, 21 or 22. And each had a league-adjusted BB%, K%, ISO, BABIP and stolen base frequency within one standard deviation of Betts’s numbers from last year.

Player	Year	PA thru 28	WAR thru 28	WAR/600
Chipper Jones	1993	4,072	33.4	4.9
Derek Jeter	1995	4,981	32.5	3.9
Darin Erstad	1996	4,190	22.4	3.2
B.J. Upton	2005	4,509	21.7	2.9
Shawn Green	1994	4,181	20.5	2.9
Johnny Damon	1995	4,828	18.0	2.2
Marcus Giles	2000	2,864	17.9	3.8
Shin-Soo Choo	2005	2,279	16.7	4.4
Shannon Stewart	1996	3,512	16.2	2.8
Asdrubal Cabrera	2007	4,071	14.5	2.1
Desmond Jennings*	2009	2,018	12.3	3.7
Alex Gonzalez	1994	3,634	8.0	1.3
Ray Durham	1994	3,993	8.0	1.2
Derek Bell	1991	3,000	7.7	1.5
D’Angelo Jimenez	1999	2,352	7.4	1.9
James Loney	2006	3,484	5.6	1.0
Sean Burroughs	2001	1,690	5.4	1.9
Troy O’Leary	1992	2,310	3.9	1.0
Tony Graffanino	1994	926	3.5	2.3
Ian Stewart	2007	1,620	2.5	0.9
Roger Cedeno	1995	3,273	2.1	0.4
Josh Barfield	2005	1,075	1.2	0.7
Carlos Febles	1998	1,892	0.7	0.2
Tony Tarasco	1993	1,024	0.0	0.0
Trey Beamon	1995	172	-0.7	-2.4
Michael Spidale	2004	0	0.0	0.0

*Jennings will play his age-28 season in 2015.

That’s some mighty fine company. Two of those players (Derek Jeter and Chipper Jones) are sure-fire Hall of Famers, and several others peaked as All-Star caliber players. But while each of these hitters put up numbers similar to Betts’s from last year, they’re not necessarily perfect comps. In fact, there’s one area where Betts is noticeably different than most of the hitters on the above list: His height.

At 5-9, Betts is very short for a major league baseball player. With the exception of Marcus Giles and Ray Durham, virtually all of the players listed above had at least two inches on Betts. To get a sense of whether this matters, let’s take a look at how height correlates with big league production for this clan.

This chart suggests that — at least among players who hit similar to Betts — it’s better to be tall than short. However, this isn’t to say we should start setting off alarm bells about Betts’s height. Betts may not have the upside of Jeter, Jones, or even Darin Erstad, but he still has plenty of things going for him. If Giles and Durham can be All-Stars  at 5-8, there’s no reason to think Betts couldn’t do the same.

Most players who hit like Betts did in the minors become very good big leaguers, and some even become great ones. And regardless of his height, Betts looks like he’s on a similar track, especially following his two months of 130 wRC+ in Boston last year. Mookie Betts has arrived, and he’s probably going to be pretty good. How good might depend on just how much power he can squeeze out of his diminutive frame.