After losing three straight games — two of which coming at the hands of the division rival Braves — the Mets picked up a huge win Thursday night. Pete Alonso went 5-for-5 with a home run and six runs driven in, tying the record for most home runs by a National League rookie (39 HR — 2017 Cody Bellinger). Perhaps even more impressive, Amed Rosario went 5-for-6 with three extra-base hits, also tagging on four runs scored.

In fact, Amed Rosario is the youngest shortstop (23 years and 268 days) to get 5+ hits — including 2+ doubles and at least one triple — in a single game since Joe Cronin (22 years and 325 days) did so on September 2nd, 1929.

Since the All-Star Break, Rosario has elevated his game on a drastic scale:

  • PA: 129
  • HR: 3
  • RBI: 8
  • AVG: .366
  • OBP: .395
  • SLG: .553
  • wOBA: .395
  • wRC+: 150

The only qualified shortstop with a higher weighted runs created plus than Rosario during the second half is Xander Bogaerts (159) of the Boston Red Sox. In the first half, Rosario’s 87 wRC+ put him in a tie alongside Adalberto Mondesi for the 19th best wRC+ amongst qualified major league shortstops (26 total). Now, he’s keeping up with the best of the best.

One thing Rosario has been instituting on a more regular basis in the second half is an abbreviated leg-kick, which has had many positive effects thus far.

May

Post ASB (photos via Baseball Savant)

For one, Rosario has been able to square up the ball at a higher exit velocity:

  • 1st half: 89.6 mph
  • 2nd half: 90.6 mph

Most importantly, in simplifying his leg-kick, he has enhanced his ability to make contact with pitches located inside the strike-zone.

  • 1st half: 85.0 Z-Contact%
  • 2nd half: 96.6 Z-Contact%

He’s also having increased levels of success off of fastballs:

  • 1st half: 1.22 wFB/C
  • 2nd half: 2.27 wFB/C

and sliders:

  • 1st half: -3.99 wSL/C
  • 2nd half: 1.41 wSL/C

Since returning from the All-Star Break, Rosario has been 2.27 runs above average per 100 fastballs thrown, a vast improvement upon his first half mark, and he’s no longer a bad slider hitter (that’s one fewer weakness for the pitcher to exploit).

The Mets, who are a mere two games out of a playoff spot, have little room for error.