Tanner Rainey is Taking the Next Step

The Nationals reliever made big strides in 2020, time to keep going.

The 2020 season offered a mix of feelings for the Washington Nationals. A year removed from one of the most interesting World Series runs in recent memory, the Nationals took steps backward. The lineup had Juan Soto, who put up the first 200 wRC+ season since Barry Bonds, and Trea Turner who was fighting for the NL batting title. Outside of that, it was a struggle. The pitching staff was depleted due to injuries and inconsistent success from pitchers not named Max Scherzer. Big bullpen pieces in Sean Doolittle and Daniel Hudson didn’t perform well and weren’t healthy. The good news is, Tanner Rainey has emerged as a good bullpen piece for the future, one worthy of being taken within the top 15 reliever picks in your fantasy drafts.

Improving Command

Tanner Rainey was drafted by the Reds in 2015 and had consistently been in the team’s top 30 prospects before ultimately being traded for Tanner Roark before the 2019 season. It’s in Washington that Rainey began to discover the potential that he has. In 2019, Rainey registered a 34.6% k-rate, a 40.7 whiff-rate, and hit 100 mph with his fastball. His ERA- of 87 was just below his xFIP- of 88. His SIERA and pCRA were right around league average but that was because of his glaring flaw as a pitcher, he walked a lot of guys. 

Tanner Rainey has had some control problems in his career. Before 2020, he had never registered a walk rate below 10% at any level of professional baseball. His 17.8% walk-rate was the highest in MLB among relievers with at least 40 innings in 2019. It is an undeniable problem in his development and needed to be addressed. In 2020, it appears he did just that. 

While Rainey faced nearly a third of the batters, he faced in 2019, his walk rate fell to 9.3%. It was the first time in his professional where he walked under 10% of batters no matter the sample size. It’s a dramatic improvement but is it sustainable? Here are the heat maps for both his fastball and slider from 2019 to 2020 courtesy of Baseball Savant. 

The biggest and most notable difference in the heat maps is the higher density of red in the strike zone for both pitches, as well as the higher the smaller density well outside the strike zone. A reason for this is the sample size of the season, but still, it’s a good thing to be throwing more pitches around the strike zone. Looking more specifically at his slider we can see that the pitch was either in the lower half of the zone or well below the zone likely in the dirt. It’s good to keep the slider down in the zone and close to the dirt when it’s being thrown for strikeouts. 

He threw 45.5% of his pitches in the zone, a career-high for him. Ideally, look for that number to grow in 2021. Just throwing more pitches in the strike zone doesn’t guarantee success. It’s making sure the pitches look like strikes which goes back to the heat maps being more condensed to the strike zone. For Rainey, his two-pitch arsenal has got plenty of potential to keep the strikeouts coming. 

A Flame Throwing Whiff Machine

Rainey’s improved command helped him become a dominant force in 2020. Rainey had a 2.88 ERA in his 20.2 innings of work, but a 2.30 SIERA, good for 5th in all of baseball among relievers, and a 2.74 pCRA showed that he pitched better than his ERA showed. A reason for that is Rainey had an incredible 33.3 K-BB% in the past season. He struck out nearly 43% of the batters he faced and had a whiff rate of over 47%. If you break it down by pitch, it’s even more impressive.

Rainey Pitch Whiff Table

How does Rainey get so many swings and misses? I’m glad you asked! (At least I hope you did after that) Rainey’s slider and fastball at around 2400 RPM, which puts him in the mid to high 80’s percentile. Rainey has a fastball with about 85% spin efficiency, or active spin according to Baseball Savant. His spin efficiency on the pitch allows him to be able to work up in the zone and his velocity makes it difficult for hitters to pick up on.

His slider’s active spin is around the average active spin for a slider. Active spin is not as important for sliders, as the force of gravity is pulling the pitch down which affects its active spin. You can understand more by watching this video here

What Rainey can do well is make his slider move. His slider moves almost 15% more vertically than the average slider. It’s velocity can make it seem like a fastball out of the hand and then it will cut away from righties late and with good break. Pair that with a fastball that drops less than the average fastball, you have a very lethal combo. Just look at them overlayed together thanks to the mastermind, Rob Friedman. (Yes, that Rob Friedman)

Watching stuff like that, makes it seem like it’s impossible to hit a baseball. Good thing I only write about it. 

Rainey’s results on his pitches dramatically improved from 2019 to 2020. Again, this is subject to a small sample size but xwOBA on both pitches decreased. His average LA on his slider went below 0 and he only gave up 4 balls in play on it, only one of them was hit in the air. A line drive from Jean Segura. Rainey struck out 16 hitters on his slider, and only 23 PA’s ended on his slider. Rainey had 16 strikeouts on only 52 PA’s. His improved command, great movement, and life led to more success. 

There’s not much to look for in improvement in his stuff. His spin has probably reached its full potential and his velocity on his pitches is more than enough. The active spin on his fastball could use some improvement if he wants to be able to locate up in the zone more consistently, similar to what I wrote about previously here. Rainey’s fastball is already effective so it isn’t necessary to improve it but if he wants to make it as good as it could be, and he does, it’s possible this is an area we see improvement from him.

 The slider is thrown just under 40% of the time and can reach into the low 90’s. It’s not an overstatement to say that it could be one of the best pitches from a reliever in baseball in the near future. Its movement as already mentioned is top tier. He doesn’t get too much active spin on the pitch to make it more of a curve. An issue that is apparent for some pitchers in baseball today. *cough Dustin May cough* 

Similar Profile to Greatness

Outside of the command issue, Rainey’s main flaw is that when he does give up contact, it’s usually hard contact.

Rainey QOC Table

This is a problem, though not as large of a problem for someone like Rainey. His ability to create swings and misses is going to give him an advantage in this and keep him from giving up hard contact more frequently. If the swings and misses are starting to disappear, then it becomes a problem. This isn’t uncommon for power pitchers. In fact, Tanner Rainey’s 2020 is very similar to Josh Hader’s 2019.

Hader QOC Table

Hader saw great success in 2019 despite this poor quality of contact metrics. Hader a 2.32 pCRA and a 1.74 SIERA, which is a lot better than Rainey’s marks in 2020. But Rainey still had sub 3 values in both statistics. Showing that it’s possible to pitch well if you are giving up hard contact. You just have to get a lot of swings and misses, which both of them do. Hader had a 42% whiff rate in 2019 while Rainey had a 47% whiff rate in 2020. The biggest difference is Hader has a lot more control than Rainey does but if Rainey can build off of his 2020 improvements, we can see that him giving up hard contact won’t be as important as it for other pitchers.

This comparison is not to say that Tanner Rainey will be as good as Josh Hader. That’s a lot to ask of anyone, but it’s to say that Rainey gets similar results to one of the best relievers in baseball. That’s something to consider when looking at some potential relievers on the board in the draft. If Rainey’s stuff isn’t as sharp, then he is susceptible to bad outings more than the average reliever because of how hard he gets hit. That still shouldn’t people back from taking the chance on him and drafting him. He will likely be given the closer role at some point in 2021, which means it’s going to give him a boost in value as well. I think he’s ready to take that step.

The Nationals are going to give Rainey the opportunity to succeed in 2020. The team has an uncertain future ahead of itself, but the potential star reliever is ready for the challenge that awaits him. He made great strides in 2020, he will look to build off those strides moving into 2021 and dominate the game again.

Max Greenfield

Former Intern for the Washington Nationals, now a Going Deep Writer analyzing the next possible breakout pitcher.

  • Avatar Jose says:

    Can you give me a few more “NL” reliever like Rainey, who are none closers and breaking out? I like Richard Rodriguez, even if he gets the closer job in Pitt.

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