Putting a guy in contain for what? His QB isn't rolling out...? You shouldn't put him in contain, you should put your end in man coverage on his RB, his slow speed will slip him under everyone and usually lead to a pick.
Send a backer to the flats and manually control a guy in the middle for the slants. Have a saftey in buzz and another olb in flat zone. The side that you think the WR goes to, put that CB in a hook or a flat zone so he will just sit over there and wait for that WR, usually will wind up in a pick 6 if he does throw it over there.
So now you have 2 guys covering the screen to the RB, 2 guys covering the 95 speed WR. A linebacker (user) covering the middle (slants and crossing routes) and you still have saftey help over the top. You will either wind up with a INT, knockdown or a little gain. With this setup you shouldn't give up a big play.
I run about 50% of my plays out of the nickle, so thats just me. Thats just how i would do it. Maybe 40%.