In 2010, he threw 93.6 mph and struck out 23.1% of the batters he faced. This year, he's down to 92.4 mph and 16.6% respectively.Although Norris would finish the year with a 19.0% strikeout rate, that still came in far below his previous norms, corresponding with the aforementioned velocity decline:
Unsurprisingly, his xFIP- in 2013 (106) was notably worse than from 2009 to 2012 (100). Because of the negative nature of pitcher aging curves, most suspected that he'd never be the same again.
Then came 2014, in which a funny thing happened. The velocity returned...
...but the results remained subpar:
His lucky ERA notwithstanding, Norris didn't do much in 2014. But why? If his velocity made a comeback, shouldn't the punchouts have come with it?
First, let's check his peripherals. They support the decline fully: While hitters didn't offer at this pitches any less than they used to (his 45.9% Swing% in 2014 didn't diverge much from his 45.5% mark from 2009 to 2013), they didn't miss nearly as often when they did (his 83.5% Contact% departed significantly from the 76.7% figure he theretofore posted). So an absence of whiffs caused this, but what caused that?
Entering the majors in 2009, Norris only had three pitches: a four-seam fastball, a changeup, and a slider. As the above velocity chart shows, all three of those quickly lost velocity, leading him to integrate a fourth pitch: a sinker. In 2010 and 2011, he threw it less than 7% of the time, but by 2012 — when his velocity hit its nadir — it had become a full member of his arsenal:
Norris's slider has always been good. Like, really good. According to Jeff Zimmerman, an above-average slider has a whiff rate of 14.4%; Norris's has resulted in a swing-and-a-miss 18.5% of the time. Two years ago, however, that took a turn for the worse, and it hasn't recovered yet:
At 30.7%, Norris's usage rate on the pitch had never been lower.
Remember, Norris regained velocity on every pitch — including his slider — in 2014. That means speed didn't create this, which indicates it may be something within Norris's control. But what?
His location of the pitch stayed the same, as did the rate at which batters swung at it. One thing did change, though: his sequencing. Earlier in his career, he relied on the slider to get tough outs; by 2014, that had changed:
|Year(s)||Slider% — Batter Ahead||Slider% — Even||Slider% — Pitcher Ahead|
In a hitter's count, Norris relied on the slider as much as ever; when he had the advantage, though (or when he was close to having the advantage), he decided to eschew it. Its replacement came in the form of his new favorite pitch — the sinker:
|Year(s)||Sinker% — Batter Ahead||Sinker% — Even||Sinker% — Pitcher Ahead|
To put batters away, Norris no longer leans on his slider, as he's deemed his sinker a worthy substitute. Of course, this means fewer whiffs — a batter won't swing and miss as often in a hitter's count, when he has room with which to work, as he would in a pitcher's count, when he's more desperate. Nevertheless, that tantalizingly low ERA from last year (7% better than average, the best level of Norris's career) might convince him that it's a worthwhile tradeoff.
So, there you have it. If Norris ever decides to get strikeouts again, he can probably do so; all he has to do is decide to put batters away with his slider, instead of his sinker. The stuff is there, but if the mind isn't willing, it won't come to fruition.