After a cooler start, Ben Zobrist, just one of the Cubs’ important additions, has heated up quickly. His batting average has jumped up to .305 in a week, up from .253 on May 2. He’s on track for his best hitting season since back in 2009, when he finished the season at .297. He just turned in a brilliant 4-4 performance with 3 runs and 2 RBIs against the lowly Padres (I know, but still). He’s already been a huge part of the Cubs’ historically hot start, but now he’s casting an even larger shadow on their success. So, where’s this come from? Are there any similar threads between 2016 so far and his 2009 campaign? Do they fall in line with observations from his worst hitting year, 2010? Turns out, they do.

Zobrist’s pitch value has largely been the same over the years. In fact, he’s been startlingly consistent with most advanced metrics over the years. What stands out, however, are his plate discipline numbers. Always hailed as a very smart guy at the plate, Zobrist is at another level so far this year, and it bears similarity to 2009. On top of that, those factors were much weaker when he batted at a less impressive .238 in 2010. He’s walking at a ridiculous rate of 17.3, the closest after being a 15.2% mark in 2009. Other than that year, he hasn’t really sniffed that point since AAA ball in ‘08, not counting a rehab stint in low-A in 2014. He’s also only striking out in 9.8% of his plate appearances, just over half of his walk rate.

The biggest reason for that appears to be how well he’s forcing pitchers into the strike zone this year. He’s seeing pretty much the same percentage of pitches inside and outside of the strikezone, but he’s doing less swinging at the outside ones. In 2016, Zobrist is swinging at 17.1% of pitches outside the strike zone, which is the lowest since 2009. For reference, the last five years look like this: 22.6%, 23.6%, 23.6%, 22.6%, 25.2%. That’s a pretty solid decrease. He’s also making contact on 90.5% of pitches he swings at. His swing percentage is pretty much the same too, he’s just being smarter than ever.

Zobrist visibly swung at more outside pitches during 2010, our reference year for poor hitting, and less back in 2009, his best hitting year until now. Here are heat maps for swings against all pitchers in those seasons, per FanGraphs: 2009, 2010, and 2016.

In the first graph, the swing numbers are pretty cool outside the strike zone; he went after a good amount high and just outside, but was pretty careful on the edges. In 2010, it gets brutal. He went after more high pitches, to the point that that area almost strays into warm colors on the graph. The spots close but still outside are even worse. He also went after quite a few more in the lower corners. This year? Each edge is ice-cold. Not just that, but the areas in the close-outside regions show way more blue than either of the other years. He’s generating a ridiculously tight zone.

Higher amounts of walks aren’t the only benefit coming from the increased discipline, either. It’s also creating better hitting opportunities as pitchers are forced back into the zone. His line drive percentage is up to 24.5%, his ground ball percentage is down, and he’s cut his infield fly rate in half from 2015. He’s also on track for around 20 home runs, a mark he’s hit twice in his career and surpassed once (but it’s double his 2010 number). It follows that the ball will leave the park more if pitchers put the ball in the zone more (generally), and that more line drive contact tends to lead to more of them too (generally).

Zobrist has always has the ability to hit well, and has generally hit smarter. But the formula he’s using this season, distilled from habits leading to his best year, is being executed even better than before. He’s hitting better and smarter, and it’s leaving him poised to be the most important addition the Cubs made last winter, even following Jason Heyward’s monster deal. At 4 years for $56 million, he was already a great value; but that deal is starting to look like downright highway robbery. If he can keep it up, he’s going to be an even bigger part of the team’s lofty aspirations this year.