Over his last five seasons (ages 31-35), he's a 2 WAR player per 600 plate appearances. And he'll keep being one for as long as his .390 BABIP holds out. I'm pretty indifferent about Johnson, but he's been a +WAR player for his entire career (though sometimes barely). He's not awful, and he's fine as a spare outfielder (though I'd prefer he was the 5th, not the 4th). His babip is high, but so is his LD%, so he's not just getting insanely lucky. The same was true last year, and was in 2008. His numbers will come down if he continues getting a lot of PT, but that's why he should be a backup. At best he's a decent backup, at worst he's superfluous.