From what I've noticed in ranked warzones on Pot5, Smash spec is not overly popular in ranked warzones. Most sentinels are better off going combat spec, and most guardians as Vig/tank hybrid. The most successful ranked teams are running a combat sent, assault vanguard, gunslinger/vanguard, and two guards in the main fight.
If smash was so OP wouldn't it be more popular??
Smash does lots of damage, but its still very squishy, and most effective when in the middle of 5 enemies who usually end up focusing the smasher.
Think about huttball w/o hybrid spec jugger. And vanguards much better damage dealers bcos they dont care tank you or light armor user.