Plenty of uncertainty surrounding the Mariners’ starting rotation going into 2017

Felix Hernandez’s gem of an outing in Oakland has helped spark the M’s resurgence. (Tony Gutierrez/AP)It seems that each year the quality or lack thereof of the Mariners’ starting rotation elicits heated debate among fans. There was never enough proven starters or not enough young arms, too much reliance on potential or trusting fading veterans.

The one constant through those years was Felix Hernandez sitting atop the rotation as the reliable ace that made the assembled unit just a little better because of his presence and outstanding performances.

But that thinking is fading. Why? Because Hernandez is no longer that same dominant pitcher. He turns 31 on April 8 and has logged more than 2,400…