A quick glance at the Cardinals’ 2017 fWAR leaderboard reveals something unexpected. Atop the list — and by a wide margin — is 29-year-old Tommy Pham. He’s amassed 2.8 fWAR in just 259 trips to the plate, easily best on the Cardinals and 15th-highest among National League position players.

It’s been a long journey for Pham, the 496th overall pick in 2006. He spent nine years in the Cardinals’ minor league system before finally making his major league debut as a September call-up in 2014.

The following year, Pham opened the season in the minors but was recalled in July and put together a .352 wOBA and 1.5 fWAR in 173 plate appearances. In limited opportunities in 2016, Pham managed a 105 wRC+, but he struggled defensively and struck out nearly 40 percent of the time.

This year, after starting the season in the minors yet again, Pham was called up in May. Since that time, he’s slashed .308/.394/.522 with a .390 wOBA and 141 wRC+. His defense and base-running have been excellent. He has 12 home runs and 13 stolen bases in 17 attempts.

It was Randal Grichuk’s demotion in late May that opened up a full-time opportunity for Pham. Grichuk is still just 25 years old and he possesses impressive power, but he’s been inconsistent offensively and ZiPS projects just a .313 wOBA from him for the remainder of the season.

Meanwhile, Pham’s sustained success has had a major impact on his once-dismal projections. ZiPS forecasted a .319 wOBA from Pham before the season started; now, it predicts a .342 wOBA.

What’s with the optimism? For starters, Pham has made some key improvements to his plate discipline this year:

Tommy Pham Plate Discipline Year PA O-Swing% O-Contact% Contact% K% Year PA O-Swing% O-Contact% Contact% K% 2014-16 358 26.3% 48.1% 70.7% 31.8% 2017 259 19.8% 63.6% 78.2% 25.1%

Positive trends all around. He’s chasing less and making contact more, which has helped his strikeout rate come down to a more reasonable level.

Pham’s chase rate from 2014-16 was actually already better than the roughly 30 percent league average, but his 19.8 percent chase rate this year is seventh-best in baseball. Before 2017, Pham’s contact rate on pitches outside the strike zone was about 15 percentage points worse than the league average; this year, he’s brought it all the way up to average.

While his contact rate on pitches in the strike zone has always been roughly league average, his overall contact rate before 2017 was about eight percentage points worse than average because he made such little contact when he chased outside the strike zone. His increased contact on those pitches, however, has brought his overall contact rate up to the league average this year.

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Pham’s always been a patient hitter. His career walk rate is 11.0 percent, and he swings the bat less frequently than his peers. His 39 percent swing rate this year is right in line with his career norm, and it’s about seven percentage points lower than the league average. Now that he’s making more contact on those swings, he’s been a tough out.

Now for the negatives.

Pham’s running a .383 BABIP this year, .357 in his major league career. ZiPS forecasts a .336 BABIP moving forward, which would pull his numbers down across the board. He also hits a ton of ground balls, and relatively few fly balls. His 53.1 percent ground ball rate this season is 15th-highest in baseball, and his 22.5 percent fly ball rate is sixth-lowest (min. 250 plate appearances).

Additionally, his 28.0 percent HR/FB ratio since 2014 is the highest in all of baseball (min. 600 plate appearances). To put that number in perspective, only two qualified hitters — Jim Thome and Giancarlo Stanton — have HR/FB ratios north of 25 percent in the last 10 years. Looking on the bright side, however, there are 20 qualified hitters with HR/FB rates north of 20 percent in that span, so it is possible that Pham could join that list, especially in this home run environment.

And there’s a reason Pham has an elevated HR/FB rate — when he does hit fly balls, he crushes them. Check out the Statcast data on Pham’s various batted ball types since 2015:

Statcast Data on Batted Ball Types Batted Ball Type EV (mph) LA (degrees) xwOBA wOBA Batted Ball Type EV (mph) LA (degrees) xwOBA wOBA Fly Ball 95.3 33.3 .659 .683 Ground Ball 86.2 -12.4 .224 .263 Line Drive 97.4 15.9 .785 .820 Fly ball/Line drive 96.6 23.3 .739 .770

Overall, Pham’s expected wOBA this year, which uses his launch angles and exit velocities to predict wOBA, is .357, and his actual wOBA is .386. Since 2015, his expected wOBA is .348 and his actual wOBA is .366.

While he has outperformed his expected wOBA to some degree, his .659 expected wOBA on fly balls since 2015 is sixth-best in baseball, and his 96.6 mph average exit velocity on line drives and fly balls is 10th-highest. Putting those together, we find that his expected wOBA on fly balls and line drives since 2015 puts him in elite company:

Expected wOBA on fly balls and line drives since 2015 (min. 150) Name xwOBA Name xwOBA Giancarlo Stanton .796 Nelson Cruz .769 Pedro Alvarez .757 Khris Davis .744 Tommy Pham .739 Miguel Cabrera .721 Miguel Sano .721 Chris Davis .720 Alex Avila .716 J.D. Martinez .713 Mike Trout .703

When Pham puts the ball in play, it’s a ground ball a little more than half the time, and his ground balls usually result in outs. When he puts the ball in the air, however, whether it’s a line drive or a fly ball, he has a tendency to do serious damage that puts him on par with some of the best hitters in baseball.

While it’s obviously no certainty that Pham will continue to crush the balls he hits in the air, the Statcast data verifies that the power is legitimate. He hasn’t faked his way to the success he’s had on balls in the air.

He’s not a typical prospect, but Tommy Pham seems to be having a breakthrough year at age 29. Improvements to his plate discipline appear to have enabled him to more consistently show off his skills mashing the balls he hits in the air. Even with some regression to his BABIP and HR/FB rate, Pham still looks like a force to be reckoned with because of his above-average glove, speed, and walk rate, coupled with his improved approach and upper-echelon power on line drives and fly balls.

All stats current through July 18.

Ben Kaspick is a contributor for Beyond the Box Score and RotoGraphs, and the owner-operator of CoveCast, a saber-slanted San Francisco Giants podcast. You can follow him on Twitter @benkaspick or @Cove_Cast.