I have had the pleasure of watching Bradley for the past two seasons. I live in Dallas, so I followed his season with the Rangers, and I grew up a Cubs fan (and, sadly, remain one). The thing with Bradley is not so much that he has an "attitude" problem; it's that he doesn't play enough.
One doesn't need to be well-liked to be successful. The Dick Williams Oakland As couldn't stand each other and won two World Series. Everyone works with jerks, and the world goes on. The problem with Bradley is that he gets hurt and can't play. He is injury prone, and there is a reason that he has had only one year with more than 500 at-bats in his 10 seasons in the major leagues.
The other problem with Bradley is that he says he's hurt and can't play, and he is the only one who thinks he is hurt. He pouts, just like the guy who calls in sick because he's mad at the boss and he'll show the boss how much the company needs him. That happened in Texas, when he had a bunch of mysterious ailments in the last month or so. Even the beat writers here, hardly a negative group, were wondering what was going on. The general consensus was that he was malingering to protect his stats in a contract year. In Chicago, the "ailments" started early and never let up. You can tell this is going on because Bradley doesn't go on the DL, never has a serious injury, and always says he'll be OK in a few days.
The problem with this, of course, is that the team has to substitute a lesser player for him in the lineup and the bench is a man down. It drove Lou Piniella crazy, and even Ron Washington was annoyed.
Will this happen in Seattle? Your guess is as good as mine. Maybe Griffey can lay down the law. Maybe Wakamatsu can figure out how to handle him in a way no one else has. The one thing I wouldn't count on is that it won't happen in Seattle because the atmosphere is "low-key." It happened in Texas, and no one pays any attention to the Rangers after the Cowboys start training camp. It doesn't get much more low key than that.