RealGM

12 manager h2h league, standard cats

Nash
Durant
Azuibuke
Caron Butler
Josh Smith
Tyrus Thomas
Al Jefferson
Mehmet Okur

Felton
Bargs
Sessions
Diaw
Matt Barnes

Is a combo of Butler, Nash, Smoove and Big Al, enough for me to make the playoffs?

Your team is more than fine. If anything look to move Nash for another scorer late in the year for that final push (assuming Sessions is playing starters minutes at that point and Felton hasn't fallen off the fantasy map).

You should easily make playoffs, the trade bit is just to help you make a push to win the league, assuming the previous things that I said and as well considering Nash may rest or play less later on in the regular season (fantasy playoff time).