Rather than only looking at outcomes, progressive front offices in baseball also look into the combination of exit velocity plus trajectory in player evaluation, using tracking technology like Statcast. After all, players could be hitting rockets right at fielders and not having results to show for them in their statistics. It's one component of process at the plate, and the Mets' front office is very process oriented. A well known example of this is that the Mets front office chose Lucas Duda over Ike Davis partially because of peripheral statistics like exit velocity and trajectory.
None of this takes into account hit placement, which some hitters excel at. Anyone who watched Ichiro hit knows how much of a master he was at placing the ball in areas that defenders were not. It doesn't take into account infield shifts, either, which can eat up well-hit balls. So exit velocity + trajectory should not be the end all, be all, but that combination can help give more information into how well a player strikes the ball, and well-hit balls are more likely to go for hits.
Here is a breakdown of results based on exit velocity last year:
And here are results based on vertical launch angles:
Batted balls with a vertical launch angle between 10 and 25 degrees are considered line drives. Below 10 degrees is a ground ball. Fly balls are above 25 degrees, with over 50 degrees considered pop ups.
Where launch angles are helpful is differentiating between different types of ground balls and fly balls. A ground ball hit with a 5 degree launch angle is a lot different than a ground ball hit at a -10 degree launch angle. According to statcast, the league hit .438 on ground balls between 5 and 0 degrees but just .168 on ground balls hit between -10 and -15 degrees last season.
This is an example of a ground ball with a launch angle between 0 and 1 degree (0.58 to be exact) hit 87 mph off the bat of Michael Conforto:
This is an example of a negative launch angle, -31 degrees, hit 84 mph off the bat of Travis d'Arnaud:
The more negative the launch angle, the quicker the ground ball slams into the ground, slowing down the momentum of the ball through the infield and making it more difficult to go through past a fielder.
I'm no expert with any of this stuff, just a humble baseball fan, so there could be flaws with how I'm presenting this. But based on the charts above, it seems that the best contact is made with exit velocities of 95+ mph between the angles of 5 degrees and 39 degrees. The more negative the launch angle, the more deeply the ball is buried into the ground in front of home plate, and those don't go through the infield very often even if they leave the bat at a high exit speed. Launch angles above 40 degrees are usually fly outs.
Here are some notable Mets hitters and how often they recorded a ball in play (BIP) with an exit velocity of 95+ mph plus a launch angle between 5 and 39 degrees with the Mets in 2015. It also has a percentage of their at-bats that ended with such a batted ball:
|Hitter||BIP||% of ABs|
Cespedes and Conforto had the highest percentages of at bats ending with a "well-hit ball", at about 24% each. David Wright was right behind them at 23%. Granderson had the most overall well-hit balls at 114, but he also had the most at-bats.
I hope this method isn't overly flawed. I think it could be a good way to get some additional information on Mets hitters and how well they're hitting the ball, because there is an element of randomness to the game of baseball that can sometimes distort outcomes. I'm looking forward to your feedback in the comments.