The practice reps are not more important than the game reps.
They're typically more plentiful, which is why the media narrative began forming that NFL evaluators don't care about the game reps.
The practices span an entire week. The game is a few hours, and you're splitting reps up so many ways in so many different directions, it's hard to get a solid foundation of evaluation from the few reps in the game. Darrel Williams for example got all of six touches in the game itself. DaeSean Hamilton got one catch. Neither affords a solid foundation of evaluation based on the event alone.
Alone is the key word though. The game reps should always be seen within the context of the practice rep, AND VICE VERSA. In the case of Rashad Penny, he had 43 snaps during the practice week in team drills. Only one of those was pass protection.
He got six snaps the entire week in 1-on-1 drills in pass protection. Having seen those drills year after year up close at Shrine practices, I can safely say the halfbacks get their *** handed to them on those drills 80% of the time. And that's probably a generous estimate. That's the same rate you saw with Penny as he only won one of the six reps.
This is a personal opinion. I don't trust practice reps even when they're supposed to be full go. Game reps always matter more. Practice reps may be more plentiful, and that's part of what makes practice so valuable, but on a rep for rep comparative basis for the purpose of evaluation, game reps ALWAYS matter more to me. Always. Especially at certain positions (particularly, running back and linebacker).