The Hidden Strengths of Hunter Renfroe

It was in the dawn of the final month in 2019 when the Rays shocked the baseball community. They traded left fielder Tommy Pham and two-way player Jake Cronenworth to the San Diego Padres for a package consisting of corner outfielder Hunter Renfroe, infielder Xavier Edwards, and utilityman Esteban Quiroz.

The trade, from a pure statistical viewpoint, is quite shocking, especially considering Pham’s pedigree. Since 2017, Pham’s posed as a threat with a .284/.381/.475 slash line, 132 wRC+, .367 wOBA (.373 xwOBA), and 5.0 fWAR/150 games. Renfroe, the only current major-league talent that the Rays acquired, has posted a .231/.291/.486 slash line, 102 wRC+, .324 wOBA (.314 xwOBA), and 1.4 fWAR/150.

As I’ve severely implied, it’s quite clear that Renfroe is worse than Pham. However, that doesn’t mean that there isn’t any silver lining with him outside of the initial evaluation. In fact, it’s the opposite.

It’s quite clear that the Rays traded Pham for contractual reasons. Given his pedigree, Pham would be easy to deal with a team that has consistently strived for a low payroll. The Rays currently have the 27th highest ranked payroll in the league at $89,187,367. This also ranks $65,790,892 below the league average. Add this to Pham’s $7.9M in 2020, age of 32, and two years of control, and it makes Renfroe’s $3.3M, age of 28, and four years of control more appealing.

One of the first intriguing facets of Renfroe is his Barrel%. This stat measures the number of barrels that a hitter has out of his batted ball events. The higher the number, the more potential for barrels as the amount of BBE increases. Since 2017, Renfroe’s is 11.7, ranking 20th and in the 90th percentile with a minimum of 750 BBE. The correlation between Barrel% and xwOBA with qualified hitters in split seasons since 2017 is graphed below.

That’s a fairly high and direct correlation. This makes sense as well, considering that xwOBA is more focused on the cause of contact rather than the on-base outcomes. The opposite of that is seen with wOBA, with which Barrel% has a 0.31 r² assuming the same conditions. His plate discipline’s progression is intriguing and definitely has a connection with Barrel% as well.

To measure Renfroe’s plate discipline, I’ll take a look at his pitches/PA. The stat is quite self-explanatory. To evaluate him, I’ll look at two different samples. One will be from 2017-2018 and the other 2019. The plate appearance minimum in the former will be set to 750 and the latter 400.

During 2017-2018, Renfroe had 3.882 pitches/PA, ranking him 124th and in the 46th percentile with a 750 PA minimum. While this wasn’t bad, it certainly is below the median. In the same sample, his Barrel% was 11.6. In 2019, however, his pitches/PA was 4.095, a 0.213 increase from the two years prior. This ranked in the 76th percentile with a minimum of 400 PA. That’s a noticeable upgrade from the prior sample and well above average. It came with a 12.0 Barrel% as well.

Barrel%’s connection to this is intriguing. Theoretically, it would’ve seen an increase with more pitches seen per plate appearance. However, with a 500 BBE minimum for 2017-2018 and 250 for 2019, it did the opposite relative to the rest of the league. In the former, his was 11.6 which ranked in the 91st percentile. In the latter, his was 12.0 which ranked in the 84th percentile.

The logic behind plate discipline is that the better it is, the more good pitches a hitter will be able to see. Theoretically, this should lead to an increase in Barrel%. Although it did this, it dropped relative to league average. This hints at more potential progression for it, which would be helpful for Renfroe and the Rays in general. However, his wOBA decreased by .007 from 2017-2018 and 2019.

Now, while his wOBA decrease isn’t good, it’s something that’s very intriguing. We’ve already established his increase in pitches/PA and Barrel%, but something else to look into is his pull%. Renfroe’s pull% has always been very good. From 2017-2018, his pull% was 44.6, which ranked 13th and in the 94th percentile with a minimum of 500 BBE. Below is a graph of his pulled ball spray heatmap.

It’s a nice visual representation of what was already shown to be a very good stat. Now, here is his 2019 pull%.

This is a noticeable visual increase from the years prior and, indeed, the stats back it up. His 2019 pull% was 53.4, which ranked 1st out of 225 players with a minimum of 250 BBE.

There are a few things special about pull%. For one, it’s reasonable to say that a high pull% is good for a hitter. Since 2017, the league average wOBAcon and xwOBAcon on pulled balls are much higher than to straightaway and opposite field. For the former, the values were .452 and .417 while, for the latter, it was .328 and .351. As those values imply, the same exists for ISO. For pulled balls, the league average ISO was .349 while, to straightaway or opposite field, it was .159.

There are more benefits to Renfroe’s huge increase in pull%, most of which coming from Tampa Bay’s shorter LF. Their foul pole is 315 feet from home plate, 19 feet less than Petco Park’s. It’s not just that either, the mean distance from the foul pole to home plate is about 15 feet lower in the AL East, going from 336 to 321. This should allow some of Renfroe’s deep fly outs to turn into base hits, helping his wOBA greatly. However, we should also account for the walls, since the Green Monster at Fenway Park is much higher than the LF porch at Petco Park.

There’s one thing we aren’t accounting for in this, however, which is launch angle. In 2019, Renfroe excelled here as well. In 2019, his median launch angle was 19.2 degrees which were roughly on par with his average launch angle. His average launch angle was 19.1 degrees, ranking in the 94th percentile with a minimum of 250 BBE. That’s quite impressive. On pulled balls, his median launch angle was 15.4 degrees while his average was 16.5, ranking in the 99th percentile with a 250 BBE min.

Average launch angle has a very strong relationship with average hit distance. In 2019, a comparison between the two with a 250 BBE minimum showed a 0.63 r², a quite correlated set of data. when looking at pulled balls, it’s even more correlated, with a 0.84 r². Using the equation of the linear trendline for pulled balls, we can determine what Renfroe’s distance (y-axis) should’ve been given his average launch angle (x-axis). Using it, we can determine it to be 196.24, 5.24 feet over his actual distance.

It’s also possible to determine the percentage of Renfroe’s pulled balls that were to the farthest part of left field. To do this, I’ll be using launch direction. This essentially measures the angle to each part of the field with home plate as the origin. +/-45 to +/-27 degrees can be considered left or right field, while +/-27 to +/-9 degrees can be considered left or right-center field. In this case, I’ll measure the percentage of Renfroe’s pulled balls on the former.

While not as special as the others, Renfroe ranks right above-average. While he ranks in the 50th percentile with a 150 pulled ball minimum, the average percentage is 41.3, 0.4 below Renfroe’s. And, the closer to the foul pole a ball is, the shorter distance it will need to leave the park.

Renfroe’s fielding is another really intriguing case. For him and outfielders in general, I’ll be using OAA * 0.9 + rARM to evaluate his defense. OAA is used to measure range, with 0.9 scaling it to runs. rARM, which is quite self-explanatory, is used to measure arm. I’ll be referring to this as fielding runs from here on out.

From 2017-2018, Renfroe had -3.6 fielding runs and -2.3 per 150 games. That’s around average, but nothing special. However, in 2019, he increased that to 11.4 and 12.2 per 150 games. That’s extremely impressive. Now, given the corner outfield’s positional adjustment is -7.5 with the maximum of innings played, it’ll be hard for his DEF to reach the 10 or above range. However, if he can be in the 0-5 range, he should be just fine.

Like I’ve established, Renfroe’s not projected to be a player upgrade over Pham. Losing Pham will likely be a noticeable loss for the Rays. However, that doesn’t mean that he doesn’t come with his own strengths that the Rays will now get to utilize. Every baseball fan is well aware of the Rays’s unique playstyle, and every one of them should be at the edge of their seat to see how they do with Renfroe.

Slash line, wRC+, wOBA, fWAR, games played, PA, rARM, and positional adjustment are found on FanGraphs.

xwOBA, Barrel%, BBE, pitches/PA sample 1, pitches/PA sample 2, pull% sample 1, pull% sample 2, league-average wOBAcon, xwOBAcon, ISO for pulled balls since 2017, league-average wOBAcon, xwOBAcon, ISO for non-pulled balls since 2017, Renfroe’s median launch angle, Average launch angle sample, Renfroe’s median launch angle on pulled balls, average launch angle on pulled balls, and launch direction on pulled balls from +/-45 to +/-27 degrees are found on Baseball Savant.