What Has and Hasn't Changed for Steven Souza

Steven Souza Jr. has had himself quite an April. With a .347/.424/.613 slash line, he finds himself seventh in all of baseball in wRC+, the best catch-all offensive metric the sport has to offer right now (all stats prior to Monday’s game). If the parameters are expanded to overall impact, Souza moves into the top five, as his 1.5 fWAR rank fifth among hitters in 2017.

It is obviously far too early in the season to be calling Souza a top-five player in baseball, but the Rays have to be ecstatic with what they have seen from newly-minted (happy birthday, Steven!) 28-year-old so far in 2017.

One of the main factors in this strong start—one that is mandated by law to be mentioned every time a Rays fan brings up Souza’s fast start—is his improved plate discipline, under the tutelage of Chad Mottola.

This is a hitter who was coming into 2017 off back-to-back seasons in which he struck out in over a third of his plate appearances. No player with as many plate appearances in 2015-16 struck out at a higher rate, and it was sapping his production.

Looking at 2017

Through 20 games and 86 plate appearances in 2017, Souza has cut his strikeout rate by nearly ten percent, as he is now striking out at a far more palatable 25.6 percent, even more impressive considering league-wide strikeout rates are up once again in 2017. When the decrease in strikeout rate is combined with his increase in walk rate this year (11.6% up from 6.6% in 2016), it’s easy to come to the conclusion that Souza has made some real changes.

Here’s where is time to drop the dreaded small sample size caveat. Although strikeout rate and walk rate can be among the first statistics to quote-on-quote stabilize, as the (baseball) inventor of stabilization reminded fans the other day, that very term “stabilize” may not mean exactly what you think it does. There is still a lot bubbling below the surface when it comes to Souza’s plate discipline.

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Digging a little deeper

Just a snorkel-depth journey into the advanced metrics raises some immediate flags. Scrolling down to the “Plate Discipline” section of Souza’s FanGraphs page shows that although Souza has improved slightly when it comes to his plate discipline in 2017, it is quite possible that those improvements may be a bit noisy.

Souza’s 2017 swinging strike rate is barely below his 2015 swinging strike rate, a season in which he posted a 33.8 percent strikeout rate. His 2017 swinging strike rate of 13.1 percent would have ranked in the bottom 20 among qualified hitters in 2016, and the only reason that figure doesn’t rank as high early in 2017 is thanks to the noisy data from hitters all over the league.

The story is the same when it comes to Souza’s overall contact rate. Sure, 71.6 percent is better than 68.6 percent or 69.8 percent, but it is still a far cry from an above-average rate. Only six qualified hitters had a contact rate as low as 71.6 percent in 2016, and the league contact rate in 2017 is up at 77.2 percent through Sunday’s games.

All that said, we know Souza is going to have a bit more swing-and-miss in his game. He can hit for power, and, when he is drawing walks, he should be able to counter an above-average strikeout rate.

What hurt Souza in years past was his inability to make contact on pitches up in the zone. Here’s Souza’s whiff-rate heat map, via Brooks Baseball, prior to this season:

For those hoping to see an improvement in 2017, let’s cut to the chase:

Those two graphics look mighty similar, as Souza has continued to struggle making contact with those hittable pitches high in the strike zone (something common across the league).

If Souza wants to further the success he has had to start 2017, getting full coverage of the plate—and being able to handle those high strikes—is going to be of the important, along with his continued effort to not go after those low pitches out of the zone.

Conclusion

One month into this season, it would certainly seems like Souza is a changed man.

One metric we skimmed over when looking at his plate discipline chart above was his swing rate on pitches outside the zone. Souza has indeed seen marked improvement in that area so far in 2017. His O-Swing% is down from 30.6 percent in 2016 (and 27.5 percent in 2015) to 24.7 percent in 2017, a percentage much better than the rest of the league this season (29.2 league-wide O-Swing%).

We can also see that pitchers have been going outside the zone with a lot more regularity against Souza in 2017, and he has responded by showing more patience. This is most notable in a first-pitch strike percentage (54.7 percent) that is miles better than his career rate (66.9 percent). That’s the sort of difference that can turn a 1.5-win player into a 3.0-win player.

These are definite improvements on which Souza can hang his hat.

With the way Souza is mashing the ball, pitchers aren’t going to be lining up to start pounding the strike zone against Souza any time soon, either. The ability to get ahead in the count is something the Rays organization has always emphasized, and it seems to be paying huge dividends for Souza so far this season.

All the same, it is important to keep in mind that Souza’s strikeout rate is benefiting greatly from his first seven games of the season. Souza struck out only twice in that stretch, but he has struck out at least once in every game since. If those first seven games are eliminated, Souza would have a K rate of 35.7 percent.

Although it’s early in the season, it’s fair to say Souza has made some improvements in his plate discipline. The improvements may not be as vast as the surface statistics suggest, so it will be important to see how the next month or so plays out before returning a complete verdict.