Warrick OP?

Easy. They did not build tank.

There is really nothing special in the damage component of WW. The only thing I can say is that if a WW killed off 3 members of your team in 4 seconds, a Vayne, Riven, Yasuo, Yi, Udyr, etc. could have probably done it under one.

Your "tanks" probably had only half a defensive item completed, or perhaps only focused on armor. One key aspect of WW is that he deals a surprisingly large amount of magic damage along with physical damage.

Wit's end, Q, and Devourer stacks would have hit your team like a truck if they didn't build MR.