After April 25, Brett Gardner was sitting at .136/.190/.254. He had lost the leadoff hitting role that he had been given out of ST, had 19 Ks to just 4 BB, and was looking completely helpless at the plate. A lot of his issues could have been attributed to Gardner using his patience too much to the point that it was becoming a detriment to his approach. He was taking too many strikes, getting himself behind in the count early, and then having no choice but to hack to try to stay alive. Not being a particularly good curveball hitter, it doesn't take a genius to figure out where all the strikeouts came from with that approach.
Since then, however, Gardner has been on a mini-roll over the last couple weeks. Over the last 13 games, he has raised his tripleslash to a much more respectable .233/.337/.389 with 13 hits (3 XBH), 8 runs scored, 3 RBI, and 10 BB to just 5 Ks. I'm not going to pretend to be smart enough to come up with a sabermetric explanation for this turnaround, but I imagine it has something to do with Gardner adjusting his approach to what pitchers were doing to him early, being a little more aggressive early in the count, and generally having better pitch recognition than he did in the first month of the year.
Gardner and Jeter had been 2 of the 3 weakest links of the Yankee offense early in the season, raising questions about whether or not either of them should be leading off. Lately, however, both have turned it around and now it might be time for Joe to re-examine his early-season strategy of having Gardner lead off against righties and Jeter against lefties. Sort of a "strike while the iron's hot" approach.