It could be a little more complicated than that, depending on fight design. If WAR has a great burst DPS, it could help skip some phases that could make fights faster. In that case, having one of the lowest average DPS would not hinder WAR that much.
The example that comes to mind is Zurvan EX and the famous "skip Soar" that could be achieved far more easily if one of your tanks is a WAR with a massively powerful opener.
