Johan Santana has served many roles during his tenure as a Met. Once, he represented hope, the missing piece to a franchise that believed itself on the doorstep of a championship, and in that autumn of 2008 he authored one of the true big-game jewels in club history, a three-hitter in Game 161 that extended the season another 24 hours.

Last June, he provided one of the few platinum memories the Mets have created in the past four years, no-hitting the Cardinals, electrifying Citi Field, reducing his manager — and more than a few of the long-suffering crew who live and breathe with the team — to tears.

In many ways, though, his most valuable legacy may be reinforcing this hard truth:

Money isn’t a vaccine. It isn’t a panacea. Santana’s continuing presence on the Mets serves as one of the final links to their most recent period of prosperity, and as a reminder that just because you have money to spend, it doesn’t always yield the result you expect it to.

“This,” Santana said yesterday, “is not a setback.”

He was talking about his left arm, the priceless commodity that carried him from Venezuela to the major leagues and once seemed certain to take the trip all the way to Cooperstown. The Mets have spent the better part of three seasons hoping, wishing and praying for that wing to regenerate.