Looks to be a one-year, $5-6M deal. This is no good. Johnson figures to be the Yankees DH, which hurts his value some, but regardless, over the last three years he's posted wOBA of .373/.374/.405. If he does that over a (mostly) full season, he'll be a 20 run bat, which would be good for basically two wins. He's being paid for a little over one win. Of course you have to adjust for age, DH (remember, players hit worse as DH than while playing the field), and league, so he's probably a little under two wins when all is said and done, and there's a non-zero chance that Johnson misses a good chunk of the season because he tears something or steps on a 30-year-old landmine somewhere in a random jungle.
At the end of the day deals like this have to make you shake your head. C'mon Seattle, the other New York, and San Francisco. Help us out here.