Cano improves Mariners, but enough?

The contract that will send Robinson Cano to the Mariners is absurdly long, but $24 million a year is very reasonable for a player who's the best in the game at his position and regularly among the top five in his league. He fills a general hole for the Mariners, who needed runs any way they could get them, but not a specific one, as he replaces a cost-effective, second-year player with a lot of offensive development ahead of him.

And he doesn't do the thing the Mariners will need the most to get an appropriate return on this investment