*In case you were curious, this post was written on Saturday night, a mere 12 hours before Zimmermann decided to have his worst start of the season against the Dodgers. So while the referenced stats may have changed, my opinion of him has not. He’s still a stud. This has been a disclaimer.

If you ask a casual baseball fan who the ace of the Washington Nationals is, the two most common answers would be “Stephen Strasburg” and “I have no idea”. And even beyond that, Gio Gonzalez would likely be the third answer on the board. Somewhere further down the list would be Jordan Zimmermann, who just quietly goes about his business as the best pitcher inside the Beltway. Yes, he doesn’t have the flashy strikeout numbers that some of his rotation mates have, but that’s just one piece of the overall puzzle.

On the season, Zimmermann is 12-4 with a 2.58 ERA, 0.97 WHIP and 95 strikeouts in 132 1/3 innings. And frankly, that last number is the most important one for both his current and future value. Zimmermann has been very good over the previous two seasons, with a combined ERA just slightly over 3.00, but he’s still been building up his workload after his late 2009 Tommy John surgery. Remember, he was the template that the Nats used when easing Strasburg back into his workload. But this year, he’s in the top-10 in baseball in innings pitched and on pace to throw over 220 innings–which would vault him up into the space that aces reside. And he’s been doing it with the best per inning performance level of his career.

So what is Zimmermann doing to move himself up the leaderboards? First of all, he’s putting up the best walk and ground ball rates of his career–and anyone who’s pretty familiar with how I value starting pitchers knows how much that turns me on. In fact, for all the press that Adam Wainwright gets for having 12 wins against only 15 walks for the year, Zimmermann has 12 wins against only 18 walks. But beyond that, he’s showing continued improvement in other areas. The percentage of swings he’s gotten on pitches outside the strike zone has increased from 29.5% in 2011 to 32.1% in 2012 to a career high 34.8% this season–that rate is good for 5th among qualified starters in the majors. The importance of that number is tough to overstate, as when batters swing at pitches outside the zone, the two most common outcomes are swings-and-misses or weak contact.

On top of the statistical side of things, Zimmermann continues to show high-end stuff, which was not always expected when he was coming up through the minor leagues. In fact, even though Zimmermann was ranked as the Nationals’ top prospect by Kevin Goldstein at Baseball Prospectus heading into the 2009 season, it was noted that he lacked elite stuff. Here’s what Goldstein wrote:

“The Good: He does nearly everything well, has a strong durable frame, and easy arm action that allows him to deliver fastballs that sit at 90-93 mph while touching 96. He throws two breaking balls, but his slider is the better option-a low-80s pitch with a strong late break. His changeup is solid, and he’s fearless with all of his pitches.
The Bad: It’s hard to criticize Zimmermann other than to point out that he’s not exactly dominant. All of his pitches are good, but he lacks that one knockout offering to project as an upper-tier talent.”

Turns out that Zimm had a next level to his stuff as he continued to move up the ranks, as that 90-93 MPH fastball has averaged over 94 MPH over the past three seasons and the rest of his stuff has ticked up from a velocity stand point as well. And that’s not all. Check out the chart below to show the bite that Zimmermann has added to his curveball as his career has gone on:

When I re-ranked the Top 500 Overall Dynasty League players at the beginning of July, Zimmermann cracked the top-10 among starting pitchers, ahead of such established pitchers as Madison Bumgarner and the struggling Cole Hamels. And while he was ranked behind Strasburg in those rankings, that’s based on potential and not current standing–if I had to choose one of them to anchor my staff down the stretch this year, it would be Zimmermann. As you’d expect to see, based on that statement, Zimmermann is actually the #6 starting pitcher in 2013 according to the ESPN Player Rater, behind only Kershaw, Wainwright, Harvey, Scherzer and Corbin.

The lack of hype surrounding Zimmermann as he continues to improve at nearly all facets of the game is something to pay attention to in your league, as there’s the potential for value dislocation here. It wouldn’t be uncommon for someone to look at his strikeout rate and just make a blanket statement about his value going forward, but that’s a short-sighted way of viewing him. Just like runs scored tend to be the stat most ignored when looking at overall value for hitters, WHIP becomes the same for pitchers–and the effect that a 0.97 WHIP can have on your roster when that pitcher is also among the league leaders in innings pitched is incredibly important. So poke around and see if the Zimmermann owner in your league doesn’t have the proper appreciate for his ace’s skills–it may be worth your while.

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