Martin's defense is not questioned, nor is it being discounted. In fact, I think most here agree that Martin's defense - speed, arm, routes, smarts, and etc... will make him a top 5 CF defensively in any city... but in Seattle where the ball tends to hang in the air longer, Martin is probably a top 3 CF defensively.
Unfortunately, if Martin has not fully healed yet from his hamate bone injury, or he re-injures the same spot, or if the league has actually figured Martin out, or whatever any other reason is for last year.... if he does not bounce back, Safeco and Oakland will especially PUNISH Martin's offense, so that he will be Brendan Ryan offense bad because the ball hangs up in the air here.
Furthermore, IF Martin had these tendencies when he was in Texas, they were limited his first few years by playing 90 games in Texas (81 home, 9 Houston).