Following Erik Gonzalez’s collarbone-shattering collision with Starling Marte, Cole Tucker was called up to the big leagues on April 20th. He instantly endeared himself to fans, fielding a groundout cleanly (a rarity in those days) in the first inning. In the bottom of the fifth, he put an exclamation point on his debut, crushing a ball over the center field wall for what would eventually be the game winner in a rain-shortened game.
But since his spectacular debut, Tucker’s numbers have trended downward. A month into his rookie season, he’s posting a slash line of .182/.229/.318. His wRC+? A miserable 41, well below league average of 100.
Obviously, Tucker is a long-term prospect, and right now his value depends heavily on his defense. But as Tucker battles at the plate, it’s worth evaluating why he’s struggling, as well as what he does well.
If You’re Not First, You’re Eighth
In his first two games, Tucker batted in the leadoff spot. In almost every game since, he’s hit eighth. (The exceptions were the games in Texas, where he hit ninth, and one in LA, where he batted seventh. He’s also had two pinch hitting opportunities, one each in the sixth and ninth spots.)
Conventional wisdom would say that Tucker’s decline is a function of hitting eighth. After all, with only the pitcher hitting behind him, it would make sense that opposing pitchers are more cautious when facing the young shortstop.
Fortunately, we can evaluate that argument. By pulling pitch data from Baseball Savant (coupled with game logs from FanGraphs), we can separate pitches by where in the order Tucker hit. I used the PitchRX package in R to plot the results, with pitches broken out by pitch class (i.e. fastballs, breaking balls, offspeed).
Note: I’ve excluded the at bats in the sixth spot and the ninth spot for simplicity.
Obviously we’re working with a limited sample size, particularly with Tucker batting leadoff, but the data indicates that the conventional wisdom is far from wise. If anything, pitchers have been more aggressive with Tucker hitting eighth, pounding the strike zone with a majority of fastballs. The heart of the plate is covered in a field of green, showing that, even with the pitcher behind him, pitchers aren’t afraid to attack Tucker.
So if Tucker’s decline in performance can’t be explained by batting order, what other factors might be at play?
First, let’s look at pitch mix. Again using Baseball Savant data, I’ve plotted the percentage of fastballs, breaking balls, and offspeed pitches as a percentage of total pitches seen. Over that, I’ve charted Tucker’s hard hit percentage (in red). This is the number of swings (including swings and misses) on which Tucker made hard enough contact to create an exit velocity of at least 95 miles per hour.
Again, we’re looking at limited samples, but one thing does leap out: The spikes in hard hit percentage all seem to line up with dips in fastball usage. The biggest exception came this past Thursday, in a game where Tucker pinch hit. Tucker saw three straight fastballs, none of which he swung at, before finally crushing an offspeed pitch.
Using Savant and R, we can also visualize Tucker’s results against fastballs. First, let’s look at Tucker’s contact quality by pitch type. Again using R’s PitchRX package, I’ve split results based on pitch type, and then added a color scale to denote the exit velocity.
There’s a couple of promising red dots in the center chart, but there’s also a lot of green space right over the meat of the plate, especially compared to his breaking ball results. Tucker isn’t making consistent hard contact with fastballs, and that’s when he’s making contact at all. Which brings us to another red flag.
The fastball issue for Tucker isn’t just quality of contact. It’s quantity as well. Taking the same data from Baseball Savant, we can look at just what happens when Tucker swings. For this, I’ve filtered out all “called” pitches, (i.e. balls and called strikes) and kept only foul balls, whiffs, and balls hit into play.
It’s not as stark as the previous charts, but one notices a massive amount of red and blue in the above diagram. To get a better idea of Tucker’s success rates, we can look at his swing and miss rates as well. First, we have Tucker’s whiff rates compared to league average on all pitches, followed by the swing-and-miss rates on swings only.
Those numbers throw into stark relief just how bad Tucker has been at hitting the fastball. Tucker has whiffed on 29.3% of swings against fastballs, a whopping 42.9% increase over the league average of 20.5%.
If there’s a bright spot, it’s how Tucker hits offspeed and breaking pitches. Tucker is lagging well behind the field against fastballs, but on breaking balls and offspeed pitches, he’s making contact at an above average rate. On breaking balls in particular, Tucker has found success. He’s making contact at an above average rate, and, judging by the exit velocity by pitch type, he’s making that contact count, too.
Again, Pirates fans should certainly not be bailing on Tucker this early. He won’t turn 23 until July this season, and he’s already proven much more dependable than Pittsburgh’s other options in the field.
But until Tucker figures out the fastball, I’d expect pitchers to continue to challenge Tucker with the fastball. Only time will tell just how long it takes for him to beat the heat.