So finally I would like to look into whether batters can actually learn how to become more patient and draw more walks after they have reached the majors. I looked at all batters who were below expectations for their careers prior to a given year and were still below expectations for that year but who were above expectations the next year and for their career beyond.

There were 1081 instances in baseball history. Here are the largest turnarounds:

Eddie Collins went from a better than average second baseman to one of the best all time at age 22 when he started to draw walks.

There are still a couple of issues with this list: 1) 22-year-olds may just be developing. We should limit the actual late walk bloomers by age or previous career plate appearance or both. 2) Some players appear multiple times. For example, Harry Davis age 25 and age 32 both are listed. Did Davis forget suddenly how to draw a walk at age 28 and then remember? Clearly, for someone to qualify, they would need to make the list just once, when they turned a corner in their career and never looked back.

We'll use those criteria to get down to just those batters who qualify next. Then we'll know if it's possible to learn to be more patient as a major-leaguer and what it means for one's career.