Junior was probably hesitant to call off the veteran even though he had a better angle.
Gracie's comment was that you can't call for it on a diving or better-than-average-catch play.
There's no better fielding 1B than Mark Grace
. I wonder if, in the heat of the moment, there is a way for both of them to communicate, "I don't know if I can get to it, do you?" and decide who has the better chance for the catch, a better angle for the throw, etc. Then call off the other.
With an outfielder coming in and a 1B going out, it's clearly the outfielder's call. With two infielders, you'd think it would be the 2B's call.