Friday, June 03, 2011
Quantifying Dustin Ackley
Posted by Brian CartwrightDustin Ackley is on a hot streak. The 23-year-old second baseman, in his second year at Triple-A in the Marine's system, had a batting average/on base percentage/slugging average of .355/.449/.606 in 30 May games after a sluggish .211/.336/.305 April. Two years after the Mariners made Ackley the second overall draft pick out of the University of North Carolina, his promotion to Seattle seems imminent.
What can we expect of Ackley as a major league hitter? Has his recent performance shown that he has turned the corner, or is it a normal up and down variation around his true talent level?
After three straight seasons hitting over .400, more walks than strikeouts each of those years, and 22 home runs as a junior, he was regarded as the top college hitter available in the 2009 draft, and was selected immediately after pitcher Stephen Strasburg. Ackley didn't play professionally until the Arizona Fall League, but posted a nice .315/.412/.425 line. It was a different story in 2010, as Ackley struggled early in the year at Double-A. He maintained his expected walk and strikeout rates, but his batting average on balls in play was near .200, which did eventually moderate. He earned a midseason promotion to Triple-A, but even in the hitter-friendly Pacific Coast League failed to put up numbers in line with expectations. Another trip to the Arizona Fall League ended the season on a high note: There, where Ackley posted numbers similar to his college years.
Age BA OB SA AB H DO TR HR BB SO
2007 North Carolina NCAA 19 .402 .448 .591 296 119 20 3 10 30 21
2008 North Carolina NCAA 20 .417 .503 .597 278 116 21 4 7 53 27
Cape Cod CS 20 .415 .586 .707 41 17 4 1 2 16 10
2009 North Carolina NCAA 21 .417 .517 .763 266 111 18 4 22 50 34
Peoria Fall 21 .315 .412 .425 73 23 5 0 1 12 19
2010 West Tennessee AA 22 .263 .389 .384 289 76 21 4 2 55 41
Tacoma AAA 22 .274 .338 .439 212 58 12 4 5 20 38
Peoria Fall 22 .424 .587 .758 66 28 10 0 4 26 11
2011 Tacoma AAA 23 .288 .390 .467 212 61 13 2 7 36 32
Different levels, different ballparks, hot and cold through out the course of the season.
Shameless plug: This is why I love the major league equivalencies I make available at The Hardball Times Forecasts. Adjusting Ackley's performances based on how others on those same teams subsequently played at higher levels, gives the following assessment of Ackley's numbers.
Age PA wOBA BA OB SA _BH _HR _BB _SO
2007 19 336 .316 .287 .325 .394 .317 .017 .057 .128
2008 20 397 .367 .309 .389 .439 .371 .018 .118 .166
2009 21 409 .347 .277 .354 .434 .341 .040 .103 .218
2010 22 674 .327 .255 .342 .392 .298 .021 .113 .162
2011 23 251 .323 .255 .340 .408 .285 .034 .120 .151
MLB .330 .269 .334 .427 .302 .038 .081 .166
While it's possible that Ackley has improved this year (like Neil Walker seemed to have flipped the switch on last spring), these numbers show his 2011 season (so far) to be virtually identical to his 2010. The numbers that jump out at me are how his base hit rate (BABiP) went from .371 and .341 his last two years in college to .298 and .285 in his first two years as a pro.
I have heard it said that one of the problems in evaluating college batting stats is that the metal bats used in college allow players to put the bat on the ball and get hits on pitches that would break a wood bat, or result in much weaker contact. My translations compare sets of players in different contexts and then apply the those adjustments to all the players, but it could well be that Ackley is one of those hitters whose batting style allowed him to take advantage of the metal bats.
I then looked at Ackley's batted ball profile, to see if that might suggest a higher BABiP than what he has shown as a pro. The major league players most similar to Ackley in ground ball rate and home runs per total line drives plus fly balls, depending on the number of players queried, consistently had a group BABiP between .305 and .310. That's higher than Ackley's .295, but only enough to add about another seven hits per season
BIP GB LD FB PU
2009 54 .463 .278 .167 .093
2010 479 .507 .148 .284 .061
2011 167 .485 .180 .257 .078
Total 700 .502 .156 .277 .065
MLB .454 .187 .282 .077
The Forecasts calculate a current true talent level of .266/.347/.408, and, given normal aging and no major injuries, expect him to maintain that production for another five or six years. That might not be the star hitter that was expected when he was drafted, but even when considering a glove of roughly -5 runs, Ackley still ties Scott Sizemore as having the top current talent level among minor league second basemen.
Brian got his start in amateur baseball way back in the 1970's as the statistician for his local college summer league in Johnstown, Pa, which also hosts the annual All-American Amateur Baseball Association. A longtime APBA and Strat-o-Matic player, he still tends to look at everything as a simulation. He has also written for StatSpeak and Fangraphs, was runnerup in the Baseball Prospectus Idol competition, and has consulted for a major league team. You can contact him at .(JavaScript must be enabled to view this email address).
I think Ackley’s best comp is Kelly Johnson at this point. We’ll see.