If you look at the advanced statistics, he was excellent from 2009-2013. Not only were his numbers good as is, Russell Martin is one of the top players in the game when it comes to hidden value. So much of what he adds to the team isn't currently factored into the numbers that you see on a stat page. Aside from his elite level framing (where he can pull "balls" into the zone and trick the umpire into calling "strikes"), he's also high on intangibles, where he's considered to be a really good game caller, a clubhouse leader, someone who is in excellent shape (he's actually trained with GSP), and in spite of all the maple-boner jokes, he is Canadian.
Something else that isn't very much talked about, is that Russell Martin is somewhat of a chameleon. Throughout the past several seasons, he's significantly altered his approach to fit the ballpark in which he's played. In 2011 with the Yankees, he posted the lowest GB% and second highest FB% of his career, an approach fitting of that backyard bandbox joke of a ballpark. In 2014 in Pittsburgh, a park that slaughters players of his profile (right-handed pull hitters), he completely flipped his approach, developing a sudden and incredible ability to use the rest of the field, evidenced by these wRC+ splits:
http://i.gyazo.com/f215a42077321d6ab0f6b541d5044299.png
Coming to the Rogers Center, a stadium in which righty pull-hitters thrive, it will be interesting to see if he can adjust once again, reverting to his older pull profile, or if he continues to use the opposite field as much as he did.