I have crabed all over the tacoma area in the past. Les Davis Pier, Old Town Dock, Dash Point, Commencement Bay, Jonny Seafood in the Foss Water way, Steilacum, Fox Island, etc.....
Steilacum and the bridge to Fox Island was decent at low tide. Wade in the water with a net or a small boat to skimm the shallow waters worked well for us. In the front of Chambers Bay is pretty shallow water for wading durring low tide also. Durring the high tide we would walk down to the RR bridge south of the ferry dock in Steilacum to crab.
Most of the piers are over fished and heavily crabed. Leagal crab are hard to come by. The best way is to have a small boat to get away from the piers. In front of the old Asarco, Puyallup River, Grain Mill, or most any place along Ruston way away from the shore line will be better then any of the piers.
One of the best places to crab used to be under the 11st bridge but i have not been there in many years.