Not for locks. While having mana is important, sta is a great stat to have - your pet gets part of that and you can Life Tap for mana. Plus, that lock is Demonology specced and heavily into pvping in the arenas. The key about the arena is take your opponents out before they do you.
"You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Things Are As They Are." -Benjamin Hoff, The Tao of Pooh