Mark Trumbo has put the Angels offense on his back this year. His walk-off home run in last night’s game against the Yankees pushed his total for the season to eight and his wRC+ of 172 sits sixth in the league, trailing just Paul Konerko, Josh Hamilton, Joey Votto, David Wright and Carlos Ruiz. Most notably, Trumbo brings an OBP of .388 into Tuesday’s action just one year after posting a .291 mark. The jokes were easy — Trumbo never saw a pitch he didn’t like, and indeed his 52.9% swing rate was among the tops in the majors.

This year, Trumbo has developed his eye, and his ability to recognize the strike zone is paying off not only with walks but with big-time power as well.

Observe, Trumbo’s swing rates in and out of the strike zone for 2011 and 2012 (from the catcher’s perspective):

Trumbo’s overall swing rate has dropped from 52.9% to 48.5%, largely from laying off pitches above the strike zone or those well inside off the plate. He still attacks pitches on the inner third of the plate and up in the strike zone, but he hasn’t been enticed by pitchers nibbling at those areas this season. Chances are this trend will stick for Trumbo — swing percentage is the very first statistic to stabilize of any we publish here. It’s a natural concept — there’s very little interaction between pitcher and hitter with swing percentage, merely the hitter deciding whether or not to pull the trigger.

This change has allowed Trumbo to focus his swings on pitches he regularly drives. Observe, Trumbo’s in-play ISO in the various areas of the strike zone:

Trumbo’s best asset is his tremendous pull power, as he showed with last night’s walk-off blast. He is slugging 1.058 on hits to pull and has deposited all eight of his home runs over the left field fence. By focusing his swings on the inner half of the plate, Trumbo is able to get more out of each swing.

At the same time, this graphic shows why it was so appealing for Trumbo to hack at pitches off the inside corner or well above the letters — when he does put them in play, they go. But with a contact rate nearly 20 percentage points higher inside the strike zone, it’s well worth the sacrifice to let a few go, take a few more walks, and wait for pitches in the zone to hack. Through patience, Trumbo increases his ability to reach base and avoid strikeouts all while maintaining his power.

Inevitably, Trumbo’s .390 BABIP will come back to earth and he won’t remain a top-10 hitter in the game. But Trumbo has made tangible changes to his approach in his second year in the big leagues, allowing him to grow beyond the power-first, walks-never player we saw last season. Simply by understanding his limits and adapting to them, Trumbo has managed to harness his power in a bigger and better way, improving himself as an all-around hitter in the process.