Effects of pass coverage and pass reaction sliders
By running the same routes and defense over and over and adjust sliders from extremes you can see the effects of sliders. I tested against main coverage and zone with sliders at 0,50,100 while the other slider was set at 50. The CPU is generally very reliable on same target and distances play to play with only 20% varying from a script (those I disregarded) with 20 passes thrown.
Man coverage results: Pass coverage Pass Reaction:
0 /50 /100 0 /50 /100
Space on catch: 4yd/3yd/3yd <1yd/ 3yd/5yd
Space on cut (out route): 7yd/5yd/5yd 5yd/5yd/5yd
Deflections: 1 /1 / 0 6 / 1/ 0
Sacks: 3 / 2 / 2 1 / 2 / 1
Subjective: Space on catch (i.e. screwing up the route was noticeably different when Pass coverage was adjusted (more of a buffer or lag). Speed of closure to the receiver with the ball in the air (not after catch) was noticeably different with adjustment of pass reaction.
Same for all variables (less predictable passing) without any trends or even subjective findings. There were more sacks with higher pass coverage but settings by 2 sacks at 100 vs 0 but zone in general had an insane number of sacks (about 1/4 plays resulted in a sack) so I am not sure this is relevant.
To increase deflection and thus decrease completion percentages (but not necessarily interceptions) increase Pass reaction slider (NFL average 3-5 per game). To create more open receivers and potentially decrease sack chances a lower pass coverage slider might be better (opinion more than numbers) and to decrease completions and increase deflections you should increase Pass reaction (didn't cause any interceptions).
Zone appears to be responsible for most of the coverage sacks but I can't tell either subjectively or objectively how these two sliders effect Zone defense. It is entirely possible Zone is mandated by player statistics and the sliders only impact the coverage during man defense.