I think it's beatable, but I do tread lightly compared to regular season.
Here's my thinking on it. Games in the NFL preseason are geared a lot toward people making starting postions, making the team, and trying new offensive/defensive schemes in a "live" environment. From a motivation standpoint, I DO agree with SleepyJ and the head coach (what's their motivation, how do they prepare teams, etc.) does factor in.
Where I tread a bit lightly is the variables that can't be controlled. We get some sense of HOW much teams will play starters, backups, etc...but if the team has ONE good drive, starters may be done. A BAD drive, and they might come back out.
My plays are fewer, and smaller during the NFLX, but money CAN be made. Anytime we think we can get an edge on the line, we WILL play it. We all would, right?!?
Interested to hear your thoughts, Fezzik.