RED MONDAY | Tyler Stephenson’s offense, Alexis Diaz’s slide from dominance, a week that coulda’ been

Welcome to Red Monday, where fans of the Cincinnati Reds can start the week with clear-eyed analysis of how the team is doing and where it’s headed.

The Week That Was 

We wrote about Brandon Williamson’s steady development under Reds pitching coach Derek Johsnon, our thoughts about how to fix the Reds struggling offense, how Reds hitters are projecting for more power, that the warning signs about the Reds rotation were there if you looked at the right stats, and bullet points about the trade deadline

The Reds salvaged a 3-3 week with a dramatic extra-inning win in Pittsburgh. All three losses involved late-game home runs by the opposition. The Reds 62 wins match their total from 2022. The Reds lost an important series to the Marlins, but were close to winning all three games: 

  • Monday The week got off to a great beginning, with an impressive start by Brandon Williamson and the Reds offense getting to Marlins phenom Eury Perez for four runs. Williamson went 6.2 and most importantly had nine strikeouts with no walks. Christian Encarnacion-Strand hit his second home run and Joey Votto mashed his 13th. The Reds won 5-2. Lucas Sims came on with runners at second and third and two outs in the 7th and struck out Yuri Guriel. Alexis Diaz recorded his 33rd (!) save. 
  • Tuesday The Reds lost a low-scoring game 3-2, wasting a good start from Luke Weaver. The offense managed just six hits and one walk. Lucas Sims gave up a two-out homer to Jorge Soler in the 7th to blow a 2-1 lead. 
  • Wednesday Another gut punch outcome. Behind a terrific 7-inning start by Graham Ashcraft, the Reds were cruising with a 4-1 lead going into the 8th inning. Again with two outs, the Reds bullpen — this time Sam Moll — gave up a pivotal home run. Josh Bell’s second homer of the game tied it. Alexis Diaz gave up a game-losing homer in the 9th. Spencer Steer (18) and Christian Encarnacion-Strand (3) homered. Joey Votto had three singles. The Reds drew one walk. Final: 5-4 Marlins. 

The Reds headed to Pittsburgh for a brief three-game road trip. 

  • Friday After manager David Bell shuffled the top of the order, the Reds jumped out for three runs in the first. A two-run triple by Elly De La Cruz and a double by Spencer Steer drove in the runs. Luke Maile added a three-run homer three innings later as the Reds took a 6-0 lead. Andrew Abbott pitched well, giving up two runs in 5.2 innings. Most important, he struck out nine Pirates and didn’t give up a walk. Final score 9-2 good guys.
  • Sunday 1 In what felt like a microcosm of the week, the Reds bullpen gave up a game-winning homer, blowing an excellent game from a starting pitcher. Brandon Williamson gave up two hits, two walks and a run in 5.2 innings. But walks by Lucas Sims and Alex Young in the 7th set the stage for a 3-run homer by Jared Triolo. It was Triolo’s first major league homer after more than 125 plate appearances. Spencer Steer had three hits, including two doubles. Will Benson hit his 6th triple. But the Reds bats fell short in the 4-2 loss. 
  • Sunday 2 In the nightcap, the Reds squeaked out an extra-inning 6-5 win that felt of huge importance. Elly De La Cruz hit his 10th homer (442 feet, 110.6 mph EV). Luke Maile and Stuart Fairchild each drove in two runs. Fairchild beat out a double play ball in the 10th to allow the Reds 6th run to score. Luke Weaver gave up four runs in 3.2 innings. The bullpen was good over 6.1 innings but did walk four batters. Daniel Duarte closed out the 10th with a terrific appearance. 
The Week to Come

The Reds play five home games this week: 

  • Monday – off day
  • Two home games against the Cleveland Guardians (6:4o pm, 6:40 pm)
  • Thursday – off day
  • Three home games against the Toronto Blue Jays (6:40 pm, 6:40 pm, 1:40 pm)
The right comparison for Tyler Stephenson

What should we conclude about Tyler Stephenson’s 2023 season at the plate? 

If you look at the scorebook, he hasn’t hit anywhere near as well as last year. Stephenson’s wRC+ was 134 in 2022 and is 82 in 2023 as of yesterday. That’s an enormous, 50 percent decline relative to league average. That’s why conventional wisdom holds that Stephenson’s performance has fallen way off. 

Is that the case? And if so, can we pinpoint any particular areas? 

In June, we took an in-depth look at the underlying numbers for Stephenson’s offense. We found that he wasn’t hitting the ball much different from 2022. Now, with two more months of data, has that conclusion changed? 

Let’s start by looking back to 2021, Stephenson’s strong rookie season. In 400 plate appearances, the 24-year-old catcher hit .286 with a walk-rate of 10% and isolated power of .146 on a BABIP of .333. That produced a composite run production of 110 (wRC=). 

In 2022, Stephenson was hurt much of the season. He missed all but 50 games and managed only 183 plate appearances. That’s not a tiny sample size, but it’s still small for a batter. He batted .319 with a walk-rate of 6.6% and isolated power of .163. Stephenson’s BABIP jumped to .409 in 2022. His wRC+ also soared to 134. To get a sense of how good a 134 wRC+ is, of the 150 qualified batters in 2022, only 24 had a higher wRC+ than Stephenson. To also show how much of an outlier his .409 BABIP was, the highest BABIP among qualified hitters in 2022 was .368 by NL MVP Paul Goldschmidt.

So, in 2022 Tyler Stephenson had been crazy lucky in where his batted balls landed. It was unreasonable to an extreme degree to expect anything similar from him in 2023. 

Stephenson’s production has slumped across the board in 2023. [stats through Saturday] He’s batting .243 with a 10.4% walk-rate and isolated power of .112. Stephenson’s BABIP is .324, similar to his rookie season. His composite run production has been 82 (wRC+). 

Let’s keep digging. 

Is Tyler Stephenson making worse batted-ball contact? Check out these metrics:

Average exit velocity, with league average of 88.4 mph:

  • 88.4 mph (2021)
  • 87.1 mph (2022)
  • 88.5 mph (2023)

Hard-hit (> 95 mph) with league average 36%:

  • 38% (2021)
  • 35% (2022)
  • 42% (2023)

Expected ISO (extra bases) with league average around .160:

  • .134 (2021)
  • .134 (2022)
  • .138 (2023)

Stephenson’s expected power has been remarkably consistent over the three years of his career. He actually hit the ball harder in 2021 and 2023 than he did in 2022 as born out by his average exit velocity and hard-hit%. 

I’ve already mentioned his walk rate. It was around 10% in both 2021 and 2023 and 6.6% in 2022 (league average 8.5%). Add to that a low chase rate (league average 28.5%)

  • 21% (2021)
  • 26% (2022)
  • 23% (2023)

What about strikeouts? Are his K numbers up in 2023? Here are a few metrics:

Strikeout rate with league average of 22.7%: 

  • 18.7% (2021)
  • 25.7% (2022)
  • 26.4% (2023)

Let’s look at Stephenson’s batting average. Recall that he hit .286 (2021), .319 (2022) and .243 (2023). When you control for the BABIP variance and look at his contact quality, you get these expected batting averages (league average .244):

  • .257 (2021)
  • .260 (2022)
  • .240 (2023)

Whiff rate:

  • 19% (2021)
  • 27% (2022)
  • 29% (2023)

If you break that down by pitch type, what stands out is Stephenson’s problems with the fastball, which he sees 60% of his pitches. His whiff rate has jumped from 12% in 2021 to 25.5% in 2023, that’s more than doubled. If you take a more granular look, Stephenson’s pitch value/100 pitches has remained fine with the four-seam fastball, but has dropped on cutters, sinkers and changeups — the pitches that vary off a four-seamer. 

Stephenson’s contact rate on balls in the strike zone has dropped from 88.6% to 80.7% (82% MLB average). His contact rate on balls outside the zone has also fallen, from 59.6% to 48.8% (53% MLB average). 

If you put the performance numbers together and look at Tyler Stephenson’s weighted quality of contact plus walks, you get these xwOBA (.315 MLB average): 

  • .324 (2021)
  • .318 (2022)
  • .314 (2023)

Conclusion Most analysts compare Tyler Stephenson’s current season to last year. But as nice as it would be to believe in his 2022 numbers, it’s clear that was a product of unsustainable good luck distorting a small sample size. To analyze Stephenson’s 2023 offense, a better focus would be to compare 2021 to the current year, with each of those seasons having about 400 plate appearances. In that case, you can draw these conclusions: 

  1. Stephenson’s on-base skill has been consistent at a 10% walk-rate which is 1.5% better than league average
  2. Stephenson’s power skill has been consistent (.135), which is 20% below league average
  3. Stephenson’s hit skill has dropped about 20 points from 2021, due to more swing-and-miss on certain fastballs

A clear-eyed analysis of Tyler Stephenson’s stats from 2021 and 2022 would have counseled against the strategy of bringing in two veteran catchers, which was premised on the huge importance of Stephenson’s bat.  

That said, six weeks remain in the season. That’s enough time for Tyler Stephenson’s 2023 numbers — and narrative — to change in a meaningful way. 

Alexis Diaz’s slide from dominance

For the first 11 weeks of the 2023 season, Alexis Diaz was one of the best relievers in baseball. Through his appearance on June 14, Diaz had struck out 46.3% of the batters he’d faced. He’d also limited the quality of contact on balls that were put in play. The expected batting average against him was .139 (that adjusts for luck and defense variance). His xwOBA was .237 which converts to an xERA of about 2.30. His SIERA was 2.07. Diaz was in the top two or three relievers in all these categories.

But the numbers in Diaz’s 24 appearances since June 16, tell a somewhat different story. While his walk-rate has remained steady, Diaz’s strikeout rate dropped to 21.8%. His expected batting average against rose to .225 and xwOBA to .302. Both of those numbers are still quite good — much better than league average. But also a clear step below his first couple dozen appearances.

We shouldn’t make a big deal out of those specific dates as if something happened from June 14 to June 16. That’s just an arbitrary mid-way point in Diaz’s season. In fact, Diaz got off to a great start. His decline has been gradual. Here is a 15-game rolling average for his strikeout rate. 

His strikeout rate starts at its highest point and has continued to decline. The descent has been gradual, with no sudden point of change. 

It’s well-known Diaz throws two pitches — a four-seam fastball and slider. Heading into Sunday, he’d thrown 421 fastballs and 418 sliders. Each pitch has been less effective as the year has gone on. His fastball xwOBA increased from .318 to .364. His slider went up from .169 to .260.

The spin rate on Diaz’s fastball, which is in the 97th percentile, has declined as the season has progressed. 

As a result, the vertical drop in that pitch has grown. Less spin means less defiance of gravity. That means it rises/rides up less.  

Likewise, the spin rate on Diaz’s slider has fallen as the season has progressed. 

That means he’s gotten less horizontal (side to side) break. 

Alexis Diaz remains a terrific reliever. He just hasn’t been the top-two or top-three guy that he was through mid-June. Whether he’s wearing down or batters are (sorta) catching up with him is hard to say. Keep in mind this is just Diaz’s second major league season and first as the team’s year-long closer. 

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[Featured image: Reds Facebook]

Steve Mancuso

Steve Mancuso is a lifelong Reds fan who grew up during the Big Red Machine era. He’s been writing about the Reds for more than ten years. Steve’s fondest memories about the Reds include attending a couple 1975 World Series games, being at Homer Bailey’s second no-hitter and going nuts for Jay Bruce at Clinchmas. Steve was also at all three games of the 2012 NLDS, but it’s too soon to talk about that.