An IF does not have to land in the infield... "can be caught by an infielder with ordinary effort" is the standard.
So, positioning of the infielders does matter. I will also adjust for the level of play, but not for the individual player, and certainly not for how the individual player reacts to the ball.
If the infielder has to turn and run out to catch the ball, it MAY not be ordinary effort.
But, in the end, it is your judgment.
And, the purpose of the IFR is to protect the offense, so the defense has no standing to complain how ever you call it, although usually when the defense complains it is when the IF was NOT called (they are looking for the cheap out), so I like youngump's response...
