Aaron Judge’s Amazing April

Remember last August when Gary Sanchez hit a ton of home runs and put up a .442 isolated-power figure for the New York Yankees? It was amazing. It was also special, so far as exhibitions of power are concerned. Consider: only four batters produced a higher single-month ISO last year than Sanchez. It wasn’t just improbable for a rookie; it was improbable for a major leaguer.

But the improbable is different than the impossible. Now another power-hitting Yankees prospect, Aaron Judge, has just finished his first real month as a starting outfielder in New York and has recorded a .447 ISO in the process — or slightly higher than Sanchez’s mark. The power is as large as Judge himself.

And while Judge has been the most impressive hitter for the Yankees, the club has received quite a few pleasant surprises. Starlin Castro, Chase Headley, Aaron Hicks, Matt Holliday, Austin Romine, and Ronald Torreyes have all exceeded expectations.

The result? A very successful first month of the season, leading to a 15-8 record. And while some of the club’s surprising performances won’t last — Judge included — the Yankees have banked some wins, increased their projections, and significantly improved their playoff odds, as the chart below shows.

The Yankees entered the 2017 season with playoff odds of 15.9%, the worst of any team in the AL East. Their strong April has put them over the 50% mark the rest of the way, however. At the start of the season, the Yankees were projected to have a .488 win percentage. Going forward, that number is already up to .509. Add in the wins they’ve already received, and their projected end-of-season winning percentage is up to .529.

Largely responsible for that positive trend is Judge himself. As with the club itself, his own personal projections now appear more optimistic.

Before the season began, Judge was looking at a 105 wRC+ and a 1.4 WAR over 420 plate appearances, the muted playing time not entirely unexpected for a young player expected to receive his first prolonged exposure to major-league pitching. He appeared ready to have an okay season, not unlike the Yankees as a group.

Not unlike the Yankees, however, Judge has built himself a considerable reserve with regard to his statistical line, having recorded .303/.411/.750 slash line and a 217 wRC+. His 1.6 WAR figure already exceeds the mark that was projected for him before the beginning of the season. Now, he’s forecast for a 116 wRC+ and 2.1 more WAR the rest of the way, pushing his end-of-season totals to a 134 and 3.7, respectively. One month of strong play has caused his end-of-season projections to increase by nearly 30 points in wRC+ and nearly triple his WAR.

Last season, Judge got a solid month of playing time in August and September, struggling through much of it. He struck out 44% of the time with power close to league average. His wRC+ was just 63, and he had difficulty adjusting to the majors.

Of course, he’s not the first player to struggle during his first taste of the majors, and he won’t be the last. What’s essential to a hitter’s success is the ability to make adjustments, a skill Eric Longenhagen identified in his write-up of Judge before the season.

Judge has shown an ability to make adjustments and deal with his lever length multiple times at various levels of baseball. He’ll probably be playing chess with opposing pitchers throughout his career. He has tremendous power, most of which should translate to games, and enough athleticism and arm strength to be a defensive asset in right field, as well.

Those adjustments have been best seen in and around the strike zone, as his plate discipline has improved significantly. His walk rate is at 14%, while his strikeout rate is down to 27%, a number more in line with his minor league numbers. Measures of plate discipline support the changes in his strikeout and walk rate. Last season, he swung at 35% of balls pitched outside the strike zone; this year, that number is down to 20%. At the same time, Judge has raised his contact rate on pitches in the zone from 74% to 86%. As a result, his swinging-strike rate has moved from 18% to 12%, just a little over league average.

While there are positive improvements to Judge’s game, that doesn’t mean his numbers are completely sustainable. Of course, a 217 wRC+ and 10 homers a month is an unsustainable pace for anyone not named Barry Bonds. Since 2002, there have been just 18 seasons featuring Judge’s combination of power and overall hitting in April — that is, just 18 Aprils where a player has recorded at least a .400 ISO and 200 wRC+. Four of those seasons are happening right now, as the table below indicates.

Ryan Zimmerman, Freddie Freeman, and Eric Thames also make the list from this season. Here’s how those players ended up at the end of the season:

Aside from noting the greatness of Barry Bonds, see that the worst mark a player recorded up after a great April is Morgan Ensberg’s 124 wRC+ back in 2006. On average, player’s lost 74 points by the end of the season, but they all ended up with good seasons. If Judge were to lose 74 points by the end of the year, he would end up with a 143 wRC+, not too far off from his current projection of 134.

When we talk about a player’s “home-run pace,” we often simply multiply the current rate by expected opportunities available. In that sense, Judge is on pace for 70 homers were he to play all of the Yankees’ remaining games, 67 homers were he to record 600 plate appearances, or 56 if he reached 500 plate appearances. If you want to look at pace based on what other players have done — which is probably a fairer way to think of it — here are the players who have hit exactly 10 homers in April since 2002.

Only David Ortiz cracked the 50-homer mark after a 10-homer April, but seven of 17 such hitters topped 40 homers. The average is 36, and only Hanley Ramirez and Chris Shelton had more home runs in April than they did the rest of the season. Is Judge going to decline a bit from where he’s at now? Of course. He has 10 homers, but only two doubles and a triple. Those numbers are going to even out as the season wears on. He’s got a 54% home-run per fly-ball rate after Ryan Braun led the majors last year with 29%. The only player with a number over 35% was Ryan Howard, who recorded a 40% mark in 2006.

Those numbers simply aren’t sustainable, but if Judge simply hits his fairly reasonable projections he’s going to have a great season, with home-run totals in the mid-30s. His April has been one of the best we’ve seen in recent history, putting him on the path to the All-Star Game and the Yankees potentially to the playoffs.