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The key to success for Paul DeJong

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Even minor improvements in the shortstop's plate discipline had a major impact last season.

Photo by Dilip Vishwanat/Getty Images

Between Jaime Garcia, Allen Craig, Matt Carpenter, Kolten Wong, Carlos Martinez, and Stephen Piscotty, the Cardinals agreed to commitments lasting a combined 31 years plus an additional eight through club options. While the total $220.5 million in guaranteed salary may seem like a grand sum of money, that’s only $3.5 million more than what the Red Sox will be paying David Price alone for seven seasons.

Such contracts have become commonplace in the Gateway City. A pre-arbitration player coming off a promising campaign gets inked to a long-term deal ensuring them financial security for life. Meanwhile, these deals present a relatively low-risk, high-reward situation for the Cardinals. John Mozeliak was still able to recoup value after down seasons from players like Craig in 2014 and Piscotty just last year. On the other hand, the Cardinals bought out All-Star seasons from Matt Carpenter that came at salaries well below what he would have received in arbitration or free agency. You don’t need more than a quick look at the 2017 American League awards to see the upside of these deals from a team’s perspective. Chris Sale (Cy Young runner-up), Corey Kluber (Cy Young winner), and Jose Altuve (MVP winner) are locked into contracts worth a combined $83.5 million.

This was the general thesis John Fleming outlined here at Viva El Birdos on Tuesday after Paul DeJong signed a historic six-year, $26 million contract with a pair of team options. I myself have doubts as to whether or not DeJong can sustain his production from 2017 and hold down the fort at shortstop for years to come, but barring an Aledmys Diaz-esque collapse, a reasonable floor to set for DeJong would be a power-hitting utility infielder. While one obviously wouldn’t envy paying DeJong $26 million for that level of production, it’s not an unpalatable dollar amount that would cripple the organization’s payroll flexibility. The Cardinals are essentially pre-purchasing DeJong’s arbitration years for about $20 million with the opportunity to snag two years of his free agency at a discounted price should he prove himself worthy. With inflation, the deal can be justified even if DeJong regresses to be a roughly average player.

Without much depth behind him at shortstop, though, the Cardinals are banking on DeJong being a serviceable MLB starter for at least the immediate future. While his 3.0 fWAR in 108 games is certainly impressive, his peripheral metrics tell us we shouldn’t expect similar performance in 2018 and beyond.

This graph displays DeJong’s rolling wOBA and xwOBA (expected wOBA based on Statcast’s exit velocity and launch angle data) over his previous 50 plate appearances at any given point from last season. The red xwOBA line, which tends to have greater predictive power, is consistently lower than his actual, observed wOBA. Even DeJong’s PHAMwOBA of .324 in 2017, which credits him for being an above-average runner, is a whopping 41 points below his real wOBA. We can likely chalk up a substantial portion of DeJong’s superficial success at the plate to generous batted ball luck.

A hybrid between the ZiPS and Steamer projection systems, FanGraphs’ depth charts peg DeJong for a .323 wOBA in 2018, leading to a final projection of -2.3 runs below average offensively. However, his projected glovework at shortstop is good for 2.9 runs above average, or a +0.6 runs above average projection overall and 2.1 WAR in 630 plate appearances.

Players’ fielding production generally begins to decline much earlier than their batting, although research suggests young power hitters may face a kinder aging curve in their early-to-mid twenties. Keep in mind that DeJong had all of 11 professional games at shortstop under his belt prior to 2017, so there is reason to believe he can more-or-less maintain his small-sample defensive metrics from last season with more reps at the position.

Regardless, DeJong’s bat is ultimately what will make or break his upside that the Cardinals are betting on. I identified the three notable “hot streaks” from the above graph when DeJong legitimately hit above his average xwOBA of .320, depicted by the horizontal orange line.

  • June 30-July 18
  • August 10-August 19
  • September 19-September 29

For the sake of comparison I also analyzed the following “in-between” timeframes:

  • May 29-June 29
  • July 19-August 9
  • August 20-September 18

Paul DeJong’s Hot Streaks: General Overview

Metric Hot Streaks "In-Between" Streaks Difference
Metric Hot Streaks "In-Between" Streaks Difference
Plate Appearences 141 296 -155
xwOBA 0.423 0.271 0.152
wOBA 0.481 0.304 0.178
AVG/OBP/SLG .364/.412/.749 .248/.281/.421 .116/.131/.328
K% 24.8 29.4 -4.5
BB% 6.4 3.7 2.7
ISO 0.385 0.173 0.212

These night-and-day numbers speak for themselves. “Hot Streaks” DeJong is the xwOBA equivalent of Joey Votto while the column to its right equals [squints] Jefry Marte.

Although DeJong’s plate discipline was still far-from-glamorous during his hot streaks, cutting his strikeout-to-walk ratio down from 7.92:1 to a much more manageable 3.88:1 made a world of a difference. (For context, the league average K:BB ratio in 2017 was 2.53:1.)

Paul DeJong’s Hot Streaks: Plate Discipline Metrics

Metric Hot Streaks "In-Between" Streaks Difference
Metric Hot Streaks "In-Between" Streaks Difference
O-Swing% 29.7 35.2 -5.4
Z-Swing% 68.1 74.5 -6.3
O-Contact% 59.7 59.1 0.6
Z-Contact% 86.5 80.8 5.8
F-Strike% 54.7 64.9 -10.2

Again, even relatively minor changes in each department can create a ripple effect of consequences—more on that in a moment. DeJong was willing to take more called strikes as his swing percentage on pitches inside the zone decreased by 6.3% during hot streaks, but in doing so he began chasing fewer pitches outside the zone. This less aggressive, more selective approach at the plate resulted in higher contact rates and more favorable “hitter’s counts” as pitchers converted fewer first-pitch strikes. By swinging at fewer pitches, DeJong also became more efficient when the bat did leave his shoulders.

Paul DeJong’s Hot Streaks: Batted Ball Data

Metric Hot Streaks "In-Between" Streaks Difference
Metric Hot Streaks "In-Between" Streaks Difference
Avg. Exit Velocity 88.9 84.8 4.1
Avg. Launch Angle 16 18.7 -2.7
Hard Contact% 45.5 32.1 13.4
Soft Contact% 13.8 23.9 -10.1
Line Drive% 29.2 20.8 8.4
Ground Ball% 30.5 35.3 -4.8
Fly Ball% 40.3 43.9 -3.6
Infield Fly Ball% 9.9 15.2 -5.3

Higher contact rates paired with a sharp uptick in hard contact and line drives in addition to a reduction in soft contact and pop-ups comprise a great recipe for success.

The Once and Future VEB Managing Editor Craig Edwards [continues to sob uncontrollably] penned an article about DeJong’s extension at FanGraphs earlier this week:

This next season, DeJong is likely to see fewer pitches to hit. How he responds will shape his season — and potentially future — as a hitter. There were some good signs from DeJong, as his plate discipline got better as the season wore on.

If his big league breakout in 2017 was any indicator, DeJong ought to remain less aggressive in his approach going forward. His questionable plate discipline will inevitably be tested by opposing pitchers, but improvement like we saw at times last year would go a long way to alleviate concerns about his contact quality and a potential sophomore slump.