Besides, as Don Evans at Smart Ball in Seattle points out, Robertson is practically a bargain compared to what his team threw out to a fairly comparable pitcher in Carlos Silva:
The last three years [Silva and Robertson] have been fairly durable but inconsistent. Some of the best projections we have available for next year have them as pretty close as well. The Mariners simply paid too much for what I think Silva is going to give them. I think the Silva deal stinks. I know it is not particularly instructive to compare anything to the least common denominator, but you would have a very tough time arguing Silva is worth an average of 5 million more a year than Robertson.