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Wei-Yin Chen’s Surprising Fastball

With an inability to develop quality arms stateside, the Baltimore Orioles have made an attempt to solve their pitching woes through the international market. Specifically, the Orioles have dove headfirst into Asia — too aggressively for the tastes of some in the Far East — bringing in two starting pitchers for 2012 in Tsuyoshi Wada and Wei-Yin Chen. Wada will spend the year rehabbing from Tommy John surgery, but the early returns on Chen have been extremely positive. Chen held the Yankees to two earned runs over 7 innings Tuesday night, extending his streak of starts with three or fewer earned runs through his first seven career starts. Chen owns a 2.66 ERA and a solid 3.41 FIP in his first 44 innings as an American professional, exceeding the expectations many had for him entering the year.

Chen is a fastball pitcher first and foremost, throwing the pitch nearly half of the time. He averages 90.3 MPH on the fastball and has run it up as high as 95 on the season — solid for a lefty — but it isn’t the velocity that has defined the pitch thus far. Chen has somehow been able to blow this pitch by hitters with regularity this season, inducing 35 whiffs on 374 fastballs — a stellar 9.4% rate on a pitch the league misses just 6.0% of the time. Considering this is one of the rare occasions in which a pitcher actually throws a big-time swing-and-miss pitch most frequently — curveballs and sliders, the typical big whiff pitches, are called secondary for a reason — it should come as little surprise that Chen owns one of the top whiff rates in the league among starters. His 10.1% swinging strike rate makes him just one of the 30 qualified pitchers (of 113 total) above 10%.

Chen has basically dared hitters to hit the high fastball. They’ve obliged, but more often than not they’ve come up empty. Observe, a plot of swinging strikes and balls in play off Chen’s fastball so far this season:

Chen has allowed 63 balls in play on his fastball against 35 swinging strikes — somehow, hitters haven’t been able to square the ball up at all, whiffing over half as often as they make in-play contact. Perhaps it’s because Chen has managed to elevate his fastball with success — although high pitches are often those that go for home runs, high fastballs are the most difficult to catch up with. Specifically, Chen dominates the area three feet above the zone or higher — roughly the top fifth of the strike zone and everywhere above it. Let’s take a look at this area, and include all swings — foul balls as well:

Of the 68 times Chen has gone significantly up with his fastball and batters have swung, a whopping 27 (39.7%) have made no contact at all or resulted in a foul tip. Another 24 have resulted in foul balls, leaving just 17 balls put in play. Thirteen of these 17 have gone for outs, leaving just four hits off 68 pitches in the uppermost regions of the strike zone.

Whether it’s actually finishing strikeouts or just getting hitters into bad counts, Chen has abused the American League in the top of the zone in his first trip around. The bigger question, of course, is whether or not it can continue. Chen will almost certainly see his 2.66 ERA rise, but by how much? His FIP- of 81 is nice, but he’s been an extreme fly ball pitcher (just 33% ground balls) and when his 4.9% HR/FB inevitably starts to climb, so will his ERA — he owns an ugly 4.41 xFIP so far this season.

However, if Chen’s strikeout rate moves to match up with his whiff rate — he’s only striking out 6.55 batters per nine innings despite the excellent whiff rate — some of the eventual home run issues should be mitigated. Can he keep the whiffs coming with the fastball? His secondary stuff hasn’t quite matched up — his slider, for example, has a horrid -6.6 linear weights value per 100 pitches, and when it isn’t being killed in play it has a relatively low 11.9% whiff rate (compared to a 13.0% league average), and his curveball has had similar difficulty drawing whiffs.

As the league adjusts, we may see Chen fall from his high early-season perch, but Chen has shown a tremendously useful fastball in his first seven starts as a major leaguer. At just 25, Chen has plenty of room to grow as well and improve his secondary pitches to complement it as well. A new and perhaps greater challenge begins as he starts to make his second rounds across the league, but his fastball is a great weapon. If he can maintain the effectiveness that pitch has had to open his career, Chen could easily continue to surprise throughout his rookie season.