Using the data from raidbots 10 man, top 100 parses on stone guards fight (Pretty sure 25 includes LFR which is not a cleave fight, but an aoe zerg fest)
If you remove specs that aren't ideal and have alternatives (such as sub rogue, frost mage etc., but keeping both druid and shammy dps specs):
Average dps: 104.5k
WW dps: 75.2k (71% of average)
Thats not anywhere close to a delta of 5-10%.
Even if you take out the cleave masters (mage and rogue):
Average dps 99.3k
WW: 75% of average
That is not viable in any raid environment.