I voted myself as average.
I mostly DM, so my tactics are generally running the monsters/NPCs vs. the party. I've definitely given them a serious run for the money at times, but I try not to get too overboard there. Just watch out if I run a dragon, as I usually handle those quite well!
I also try to the play the monsters based on their intelligence. A bunch of 6 INT monsters aren't going to have nearly as good of a strategy or tactics as a 16 INT creature. Thus, my packs of humanoids don't always have great tactics, but enemy NPCs are another story.
I'd say I'm much better at setting up challenging encounters (strategy) vs. actually running the encounter (tactics) as well. In the heat of battle, I'll sometimes overlook options or fail to focus on the best target, and after the fact I'll realize, "Doh! I could have really hosed them if I had done it that way instead."