How Much Should We Buy Into Rowdy Tellez’s Breakout?

The Blue Jays’ lineup is crowded, with quality hitters established at every position except catcher and third base even before the additions of George Springer and Marcus Semien this winter. With those players in the fold, there’s bound to be a playing time crunch. The obvious loser in this competition is Randal Grichuk, who isn’t quite a starting centre fielder but is a little over-qualified to be a fourth outfielder, and who will now be pushed out of everyday playing time as long as the lineup is mostly healthy.

The other guy who stands to lose out is Rowdy Tellez. He’s limited to first base defensively, but the chain reaction of adding Semien to move Cavan Biggio to 3^rd cements Vlad Guerrero jr. as the starter there. That leaves him fighting for DH at bats with Teoscar Hernandez, Alejandro Kirk, or whichever other starter is getting a day to rest his legs. He should still get his shots, especially given that he’s one of only two left handed hitters on the roster (if ‘hitting’ is too strong of a word for what Reese McGuire does at the plate), but his path to everyday playing time is murky at best.

That’s too bad, because he somewhat quietly had a major breakout season in 2020. He produced an .886 OPS, sliced 13 percentage points off his strikeout rate, walked the most he ever has, and was one of just four hitters to hit a ball over 117mph. In spite of all that, he doesn’t seem to have inspired much confidence in the front office or the fanbase. That lead me to wonder: what’s behind Rowdy’s improvement, and to what extent can we expect him to carry it over into 2021?

Rowdy only had 127 plate appearances in 2020, so any analysis is going to be constrained by small sample sizes. The biggest change, though, was in an area where conclusions can be drawn very quickly. He cut his strikeout rate from 28.4% to 15.7%. Strikeout rates reach stability (meaning the point where more than half of any variance from average is attributable to skill rather than luck) in about 100 PA, and the underlying components like chase rate, zone swing rate, and contact rate, are even faster. A player with a true talent strikeout rate of 28% will post actual results that vary by a few percentage points from month to month, but the odds of that player only striking out 20 times in 127 tries are a little less than 1 in 1500. Right off the bat, it looks like there’s something real here.

There are a couple things driving the change in results. First, he made better swing decisions. In 2018 and 19, Tellez swung less often inside the zone than average (about 63% vs a league average of 66%), but in 2020 he got a lot more aggressive, raising his zone swing rate to 70%. He did that while cutting his chase rate from just over 37% in 2019 to 34% in 2020. He still chased more than average, but on balance a much higher percentage of his swings were at pitches he could do something with.

The graphs below show his swings/take decisions in 2018/19 and 2020, broken down by pitch type. On fastballs, it looks like he chased less often inside or way above the zone. Against breaking balls and off-speed pitches, he chased less down, and especially down and away, and it looks to me like he got frozen a less often on breaking balls inside the zone as well.

The other change is that when he did swing, he missed less often. His contact rate inside the strike zone went from 78.7% in 2019 up to 85.5%, better than league average. He also made more contact outside the zone (61.4%, up from 54.7%), although contact rates outside the zone tend to bounce around a fair bit. Looking a little deeper, this also seems to mostly be the result of his swing decisions. In the graphs below, you can see that before 2020, he whiffed on a lot of fastballs right along the top of the zone and just above. In 2020, there aren’t a lot of swings there. He still missed a little bit on fastballs outside, but most of his swings are near the middle of the zone, where he makes a lot of contact. Similarly, he missed on a lot of breaking and off-speed pitches down and away before 2020, but then just stopped going after them. When he did chase, it was mostly on hangers up and outside he could reach out and get a piece of.

So we can see that Tellez improved his plate discipline, swinging at more pitches he can hit and fewer that he can’t. The logical next question is whether players who have made this kind of improvement have been able to sustain it. To investigate that, I looked at hitters who took at least 100 PA in three different seasons between 2000 and 2020 (which didn’t have to be consecutive).

On average, those players struck out about 0.9% more often in year 2 than year 1. That makes sense, because individuals strike out more as they get older and because the league as a whole is striking out more each year. Most players didn’t change much, though. Only 10% changed their strikeouts by more than 5.7% in either direction from year to year. Only 0.6% reduced their strikeout rate by more than 10%. Encouragingly, those hitters mostly maintained their gains in year 3. Their strikeouts bounced back up by only 3.6% on average, meaning about three quarters of the improvement stuck. Rowdy only barely clears the 100PA threshold, so there might be more random variation at play for him compared to hitters who maintained their changes over a full season. He also had one of the ten largest improvements in the sample, though, so even with more natural reversion toward the mean, he has can still maintain a lot of his gains over his 2019 level into 2021. If he can even keep it around the league average of 23%, his impressive power on contact should make him an asset in the lineup.

About that power. One area where Tellez didn’t really change was in his quality of contact. He maintained his 90.7mph average exit velocity, and raised his hard hit rate from 41.6 to 45%. Both numbers put him around the 80^th percentile of hitters.

He’s also been good at producing that hard contact at angles where it’s useful. The diagram below shows all the batted balls in his MLB career by launch angle and exit velocity. There are two key things to note. The first is that there’s a nice, tight cluster between about -10 and 30 degrees, the range from hard grounders through productive fly balls. Tellez doesn’t drive many balls into the ground and doesn’t pop many up, keeping the ball in range where good things can happen. By Baseball Savant’s batted ball classifications, his rate of barrels, the best type of contact, did slip in 2020, but remained above average. A lot of those lost barrels just seem to have ended up as ‘solid’ contact, while re stayed below average in terms of balls ‘topped’ into the dirt or hit under for weak flies.

The second thing is that there are big dots just inside and outside the 110mph line. Those are balls that are absolutely crushed. Almost half of MLB hitters can’t even reach 110mph, but Rowdy gets well above it pretty regularly. The most impressive part of his whole profile is the bright red dot furthest out along the 30 degree line. That represents low fly balls hit over 115mph, the kind that will clear the fence in the deepest part of any ballpark in the league by 50 feet. Over the past four seasons, there have only been 24 balls hit in that category in total. Five players have done it more than once: Aaron Judge, Giancarlo Stanton, Joey Gallo, Jorge Soler, and Rowdy Tellez. He hit one in April of 2019, and one in August of last year. That’s the elite raw power that made it impossible to give up on him when he was struggling in AAA for two years, and it’s the reason to keep making space for him in the major leagues.

The answer, then, is that we have good reason to believe that Tellez might be a very good hitter now. He had significant weaknesses in 2019, and in 2020 he made huge strides towards addressing them. The small sample should give pause, but the changes are of a kind that can be trusted very quickly, and the magnitude is so large that even substantial regression won’t completely wipe them away. By improving his weaknesses, he created more space for his genuinely exceptional strengths to shine.