[SwimsWithPhins]

I suspect that QB SPD and/or AGI might be helpful. Sometimes the play is successful only because the QB backpedals fast enough to avoid the pass rush until the receiver is open. High QB AWR is desirable too: I've had my QB pass to an alternate receiver downfield when the screen receiver is covered.

For HB screens, extreme HB SPD, ACC, and maybe high RTR should be helpful so the HB can run his route faster than the pass rush can close on the QB. The screen receiver, HB or WR, should have good moves or BTK for after the catch.

Certain screens are more successful than others:

1. WR screens--the WR screen "route" is very quick;
2. screens where the guard stays in pass protection--slowing the pass rush some;
3. screens where the FB or HB blocks to the play side--blocking for the pulling G or T.

As for the defense, I think screens are successful mostly against zone blitzes because:

1. there is no DB assigned to the screen receiver;
2. there is no DB covering the "flats" zone (zone blitz is usually cover 3 over hook/curl zones);
3. the DE or DT in front of the pulling G or T may drop back into coverage, delaying the pass rush;
4. if you guess right, the blitz may overload the wrong side of the line, leaving no pass rush in the gap left by the pulling G or T.

I've had screen passes create good YAC and break for long TDs, kind of a boom or bust situation, but it seems they are still more likely to result in a sack or a completion and tackle behind the line, even after they are mastered. Maybe I'm just not good enough at recognizing the defense's tendency to call zone blitzes.

(BTW, my experience is mostly with "picker19's" sliders.)