Tom Cable is a tough, old-school coach with a reputation as a bit of a hard ass. That is a lot of different ways to say the same thing. Throw in disciplinarian and no nonsense, too. That's generally a good profile for an offensive line coach, and seeing how Cable was able to coach the Raiders from arguably one of the worst to arguably one of the best performing offensive lines in the NFL, his profile and performance match up.
His first stint as an offensive line coach in the NFL was in 2006 for the Atlanta Falcons. He was hired by Jim Mora to take over for Jeff Jagodzinski who took over after the surprise retirement of Alex Gibbs. Cable learned zone blocking under Gibbs. Gibbs, Cable and Jagodzinski worked under former Seahawks offensive coordinator Greg Knapp. This is how the NFL works. If you follow any coaching tree far enough, you will find that it eventually grows into every other coaching tree so that it's less a forest and more a single, gigantic tree with branches named Josh McDaniels and roots named Pop Warner.
Is he good? Hard to say. He's almost guaranteed to be an improvement. The Seahawks hired Gibbs to be their line coach and running game guru, but he retired suddenly just before the regular season started. His absence hamstrung the run game and through it the offense. Seattle wasn't the worst team in the NFL at running the football, but they were a consensus bottom five. The run game didn't work, it didn't in any way set up the pass, it couldn't be relied on to kill the clock, and its most tangible impact was forcing passing down and making short yardage seem all but inconvertible.
With Cable will likely come some changes. We know Chris Spencer is a free agent and that one of his few supporters, Jeremy Bates, was fired. We also know that Max Unger is waiting in the wings. We know that Cable resurrected the career of Robert Gallery and Gallery is a free agent this off-season. Mostly though, we know that the Seahawks have a left tackle, Russell Okung, and four spots on the line to be filled.