And herein lies the weakness for DRS, particularly for infielders.
I think it's safe to assume that the lower the exit velocity, the more likely a batted ball is going to be an out statistically. You don't need to look any further than the last out of the game last night to know that isn't true, particularly for infielders. In fact, it may be more of a parabola for exit velocity and likelihood of making an out for infielders.
Last night Ortiz didn't have to go to his left or right (range) to make the play - he had to charge it because it was so softly hit. Charging and bare-handing a ball to make an accurate throw to 1B is very, very difficult. If a ball is hit too softly (low exit velocity), an infielder has very little time to make the play because they have to charge the ball before throwing it.
Horizontal launch angle is also flawed because it depends on where the infielder is positioned. On one play an infielder may be shaded towards the bag or the hole depending on the pitcher (LHP vs RHP) or baserunner (holding a runner on, threat of a SB). Last night, the horizontal launch angle would have showed that it was hit right at Ortiz, and likely statistically a high probability of being an out. Anyone who watched knows that was far from the case.
My guess is that the last play of the game, based on exit velocity and horizontal launch angle, would have showed a very high probability of making an out. The reality is that it was an incredibly difficult play that had a high probability of the runner getting on base.