It really depends. I have a striking background and even though I was good in class, I would freeze up initially during sparring, or only focus on offense and get countered. For grapplers, it may be even more difficult to cope with striking right away since they're so used to gaining dominant positions without necessarily, high impeding physical harm. But interestingly, in mma, historically, the highest caliber fighters started out grappling first and then added a striking game. Jones, Cormier, Rockhold, Weidman, etc. You also have fighters who are proficient (by MMA standards) strikers but work TDs into their gameplan for versatility and dominance, (GSP, Rory, etc.. So, maybe there is no hard fast rule.