I'm not convinced yet that it's personality. It could be circumstance instead. 

I think last year, coming off the SB win where the D carried the O there was long as they just didn't turn the ball over, Trevor was coached to play it very safe (especially under Kubiak).  Nearly every long throw that missed was thrown to the long side, which suggests to me that he (and PL) were coached to "err on the long side" and above all - DON'T TURN THE BALL OVER.  

Trevor does have a calm, low-key personality.  But I don't think that necessarily means a "play it safe" one.  I'll be curious to see what kind of gameplan McCoy has for him.  I suspect it won't be quite as "play it safe" as we saw last year.