SANTA CLARA -- Brock Purdy is an elite play-action passer. Unfortunately for the 49ers, Kyle Shanahan hasn't called many play-action passes this season.

Through six games, Purdy's play-action passer rating is an outstanding 120 while his drop-back passer rating is a solid but unspectacular 96.7. Given the discrepancy, you'd think Shanahan would call a ton of play fakes. But so far, purdy has attempted just 30 play-action passes and a whopping 155 drop-back passes according to Pro Football Reference.

What is Shanahan thinking?

“We just try to run what we think looks good on tape," Shanahan said. "It kind of just depends on how people are playing us and sometimes we think it looks really good, sometimes we think it's not so good. So it's not like we don't just do things every week because we do it. I think it's just been just a matter of how the schedule's played out.”

TRANSLATION: Shanahan feels confident calling play-action passes only against certain defensive looks and won't call them against others. Which means the other team can dictate how many play-action passes Shanahan will call.

If a team rushes four defensive linemen and drops seven defenders into zone coverage, Shanahan will call play action all day. But if a team disguises its coverages and puts six defenders on the line of scrimmage before the snap and threatens to blitz, Shanahan won't call play action much at all. He doesn't want his quarterback to turn his back to the defense while it blitzes or rotates coverages.

Sounds like defensive coordinators have Shanahan's number.

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This article was originally published on www.si.com/nfl/49ers/ as Kyle Shanahan Explains Why the 49ers have Decreased Play Action Passes.