No he didn't.

The passes he couldn't reach were not good passes.
He ran good routes, caught the ball well, and had good RAC.
Also had GREAT blocking.
Was it his "A" game? No. For Kupp it was his B- or C+ game. Not bad, just not great.

I can tell you right now that this guy's body felt horrible. That he played that well is a testament to his dedication and toughness.
I'll bet a dollar to a donut he will be the Rams leading WR when they play the Giants after he's had 10 days for his body to recover.