When Felix Hernandez broke into the Majors as a 19-year-old, he threw the ball really hard. Here’s the Pitch F/x plot of his start against the Oakland A’s on April 2nd, 2007, the first for which we have Pitch F/x data available.
The fastball was 95-100, the slider was 89-92, the change-up was 86-89 (ignore the “FS” labels, as the algorithm wasn’t so good back then), and even his “slow curve” was 82-87. Felix was the embodiment of a power pitcher, and while his three off-speed pitchers were all notable in their own right, Felix’s mid-90s two-seamer was his defining pitch. There just weren’t many guys in the game that could run a sinking fastball up there at 95 MPH, and that pitch helped him run a 60.8% GB% that year.
Now, here’s Felix’s Pitch F/x plot from his start against Oakland on Saturday night.
The change-up is still in the upper-80s, while the slider and curve are both down a couple of ticks on average, but not too terribly far from where they were five years ago. However, the fastball is 90-93, and because of its close proximity to the change-up, it’s basically indistinguishable in the chart. Instead of two distinct clumps, there’s just now one big mess of pitches in the 90 MPH range with similar movement and velocity. In fact, the similarity of the two pitches basically broke the the Pitch F/x algorithm, as it ended up classifying 47 of his 102 pitches as change-ups due to an inability to tell the change from his fastball.
In reality, if you just look at pitches between 86-90 MPH and break out the obvious sliders, it looks like he threw 26 change-ups on Saturday. Despite general acceptance of the belief that a change-up needs a lot of velocity separation from the fastball in order to deceive hitters, Felix’s change on Saturday night was still as devastating as ever. Of the 26 real change-ups, he got swinging strikes on eight of them, a staggering 31% whiff rate. On the 76 fastball/slider/curves he threw, he got three swinging strikes combined.
It’s not just the lack of swinging strikes that set his fastball apart on Saturday night, however. As noted, Felix came into the league as an extreme groundball pitcher. As his velocity has declined slightly over the last four years, he’s settled in as more of a 50-55% groundball guy, but has still been able to get a lot of grounders with his sinker.
On Saturday, though, Felix allowed 19 balls in play (excluding Eric Sogard’s bunt), and only five of them hit the turf. The 26.3% GB% wasn’t a career low in a start for Hernandez, but he’s only gone through a start with a GB% below 30% on five other occasions in 6 1/2 years as a big league pitcher. It is an unusual outcome for Hernandez, to say the least.
On it’s own, though, it doesn’t really mean anything. Felix had a start against San Diego last year where he induced only four ground balls on 15 balls in play, and yet it was one the best performances of his career. While GB% stabilizes very quickly, one game variance almost certainly isn’t predictive of anything. And, we also have to keep his opponent in mind – the 2011 Athletics had the second lowest GB rate of any team in baseball, and then added extreme fly ball hitter Josh Reddick and looking-like-a-flyball-guy Yoenis Cespedes to their roster over the winter. The opposing batter certainly has an effect on batted ball trajectory, and the A’s aren’t a team that hit the ball on the ground a lot, so we have to reset our expectations for what a normal GB% for Felix against them might look like.
When combined with a significant reduction in velocity, though, it’s something to keep an eye on. A 95 MPH sinker is just more likely to get a ground ball than a 90 MPH sinker, and if Hernandez’s fastball is going to be more low-90s than mid-90s, we would expect him to get fewer ground balls as a result. However, the if part of that statement is still a big if, as early season velocity is generally lower than mid-season velocity, and Hernandez might very well come out throwing 94 again in his next start. Back in 2008, Justin Verlander started the season throwing 92 and ended it throwing 95. Madison Bumgarner famously lost his fastball for a few months at the end of 2009 and beginning of 2010, then had it reappear later in the season. Declines in April velocity are not always harbingers of significant problems to come.
However, Felix wouldn’t be the first power pitcher to go through this kind of dramatic transformation. Tim Lincecum came into the Majors with a fastball that averaged 94 and regularly got into the high-90s, but has morphed into a pitcher who relies heavily on a change-up that is among the game’s best as his fastball has moved more into the low-90s over the last couple of years. Hernandez’s secondary stuff is good enough that he doesn’t have to rely on a big time fastball in order to get hitters out, and like Lincecum, he could probably adapt his game to play more off the soft stuff if his fastball remains less of a weapon that it has been previously.
While you can throw most early season performances out the window as completely non-predictive, significant changes in velocity are one thing that are at least worth monitoring going forward. If his fastball comes back and he gets the A’s to hit the ball on the ground regularly on Friday night, then this may all be relegated to the dustbin of weird April flukes. But, considering that Felix spent all of spring training in the 88-92 range and hasn’t flipped a magic velocity switch with the start of the regular season, this will continue to be a story until he starts sitting at 94 again.
If the velocity never does come back, we’re going to have one very interesting experiment in change-up effectiveness, especially if that pitch continues to be the primary weapon he uses when going for a punch-out. Even Lincecum’s change has had 7-8 MPH of separation from his average fastball speed. Can Felix keep racking up strikeouts with a change-up that is so close in velocity to his fastball? Will he even need to?
We don’t have the answers to these questions, but it is a situation worth keeping an eye on.
Dave is the Managing Editor of FanGraphs.