As you follow the career paths of any hitter who rises rather quickly through the minor leagues, usually you notice that there is an initial adjustment period the player goes through at each level, followed by relatively steady production at a higher level. I posit that, to get a truer sense of how that player is doing at a particular level, such a player's offensive numbers ought to be looked at with the numbers accumulated during his adjustment period left out.

Mookie Betts is just such a player. I'll do that with his numbers ... but how to decide when each adjustment period ends?

It's more art than science, this task. So here are my opinions on how many games his adjustment periods have lasted:

*Includes 16 games in the Arizona Fall League prior to the start of AA

Betts played 16 games in the Arizona Fall League in 2013, after his time in High A and before beginning AA. The typical players there come from AA and AAA, so it's appropriate to include these 16 games as part of his AA adjustment period. It's also appropriate to do so because otherwise he appears to have had no adjustment period for this level. Betts credits his time in the AFL for allowing him to adjust so immediately.

Here are some charts showing some of Betts' statistics before and after these adjustment periods, with each data point representing rate statistics over groups of 8 to 10 games (these groupings also chosen using more common sense than anything else):

The straight horizontal lines are provided for reference. These represent the major-league average values for BA (blue line), OBP (red line), and SLG (green line) over the 2013 and 2014 seasons combined. The vertical lines represent my judgment of where the dividing line is between Betts' adjustment period and the period after it.

(Arizona Fall League numbers were acquired from the Arizona Fall League site on MLB.com. All other numbers were acquired from Baseball-Reference.com.)

Error bars for On Base Percentage over these numbers of plate appearances range from around .050 to .070, and error bars for Batting Average over these numbers of at bats range from around .045 to .065. Slugging Percentage is a highly volatile statistic that you can't read too much into over numbers of at bats that are this low, but I have included it in these graphs for the curious.

I hope these graphs are at least somewhat convincing that there has indeed been an adjustment period at each new level for Betts, that it is a real phenomenon. So assuming this to be the case, what are Betts' overall numbers at each level after removing the adjustment periods, and how do these compare to his overall numbers and his numbers during the adjustment periods?

During adjustment period:

Overall:

After adjustment period:

His overall numbers are solidly above-average at the major-league level and far above average at every other level. But post-adjustment-period, his numbers are at an elite level. If this is the true Mookie Betts at 21, then he promises to become one of the best, if not the best, leadoff hitters in the game. And he'll cost far less than the Red Sox would have had to pay a declining Jacoby Ellsbury.

Will he be able to sustain this rate of production? We must, after all, consider the adjustment every player experiences only at the major league level: when the league "gets the book on you", when they find out your weaknesses and learn to exploit them. Most young players see a significant downturn in their numbers when this happens, which lasts until they can adjust to the adjustments. The thing is, it should have already started for Mookie, and yet he keeps producing at a high level. Could it be that he just doesn't have much in the way of weaknesses to exploit? In the analysis of many, he doesn't. He has become exceptional at making contact due to a combination of an excellent grasp of nuanced instruction, deliberate efforts to improve, and outstanding athleticism, which has left him with almost no weakness for pitchers to exploit, and that weakness being easy for him to adjust to. Having advanced four levels in a little over one calendar year, and still being only 21, and still learning, it seems that Mookie Betts is just going to improve on his already elite level of production. This isn't the kind of player you trade because you don't have room for him. This is the kind of player you make room for, and keep for as long as you can.