I have followed the Seahawks the past couple of years as I tend to follow Notre Dame players in the NFL. Seneca Wallace is a solid backup (I don't know about best in the league), is a kind of Tony Romo-lite kind of guy. He certainly doesn't suck, is athletic, and has put up nice numbers in the WCO. I'd start him over Anderson in a heartbeat. He does have a problem getting it in the endzone though. He tossed only 1 TD per 40 attempts last season, while Hass was better than 1/30, and even Quinn was better. And Wallace had a much better receiving corps.
Is the thought that this means the Browns will draft a QB and develop him under Wallace? I'm not even certain Wallace would win out a QB competition against Quinn, even if Wallace is comfy with the offense. And he's widely regarded as having a low top-end. So I'm not sure what to make of the move.
the defense was amazing. It may have been better than Smith's Junior season. I don't care if Notre Dame had 500 men on the field on defense, all Pro-Bowlers returned from the NFL: they were not amazing. If you think that having a good defense cannot do great things for a QB's growth in very short order, see guys like Rothlisberger, Rivers, and Flacco (and if you extend it to college, the list swells to become ridiculous).