Since his call up from AAA Sacramento in mid-May, A’s outfielder/DH Jack Cust has seemingly reinvented himself as a hitter.

For those of you who don’t follow the A’s closely, Cust was a 4-A thumper who Billy Beane obtained from the Padres back in 2007 for a box of Cracker Jacks.

Cust immediately became a minor star for the A’s, hitting 26 HRs in fewer than 400 ABs and posting a .912 OPS as a 28-year-old rookie.

However, since his huge 2007, Cust declined the next two seasons, with his OPS dropping to .851 in 2008 and .773 last season.

Cust had a poor spring this year and found himself demoted to AAA Sacramento to start the 2010 season, an assignment which Cust accepted because it was the only way to ensure that he would continue to collect his $2.65 million salary.

The A’s love guys who get on base, and I suspect they made it clear to Cust when they sent him down that it was something he had to improve if he was going to remain in their organization.

Cust clearly took it to heart, because he looks like a completely different hitter since his return to Oakland.

Notwithstanding the fact that Cust has hit three HRs in his last four games, he’s currently hitting .287, by far the best of his career (his previous high in any season in which he had more than 100 ABs is .256 in 2007). He’s hit only five jacks so far this year.

Previously, Cust was a hitter who looked to crush the ball when he was at bat. He was extremely selective about the pitches he swung at, drawing a lot of walks, but also striking out at a tremendous rate. This year, he’s obviously trying to take something off his swing to deliver more base hits.

His 2010 HR rate per 100 ABs is the lowest of his career, and since he’s hitting fewer HRs (and also likely taking fewer pitches in the strike zone), Cust’s walks rate is also at a career low, although it’s not really much lower than last season when he wasn’t hitting. 

In the meantime, his on-base percentage stands at .388, the highest of his career since 2007, when he posted a .408 OBP.

It’s unusual for a player of Cust’s age (31) to change his approach so dramatically from one season to the next, so Cust’s new focus on hitting for average may be a fluke based on a small sample size (only 143 ABs so far this season). 

Cust is a good hitter, however, and I do believe that some of the change is a conscious effort on Cust’s part.

Another factor, however, is that Cust is also being used almost exclusively as a platoon player for the first time in the last four seasons. Only 15.4% of his at-bats this year have come against left-handed pitching, as opposed to 28.8% of his at-bats over the previous three seasons.

Needless to say, Cust has an extreme platoon advantage with a 141-point OPS difference (.866 to .725) when he bats against righties as opposed to lefties over his career. In other words, Cust is a great hitter against righties, but is only a replacement-level player against lefties.

Given Cust’s lack of speed or defensive skills, it seems clear that 80% or more of his major league plate appearances going forward should be against right-handed pitchers. 

Any less than that, and he isn’t likely to hit enough to help a team much.

Cust has a lot of value as a left-handed hitting platoon player, and his value in that regard would increase considerably if he could teach himself to play first base, along with the corner outfield positions.

Read more MLB news on BleacherReport.com