Mariners cut four pitchers, including Chris Heston and Cody Martin

Mariners pitcher Chris Heston at a live batting practice at spring training. (Ken Lambert / The Seattle Times)The Mariners on Sunday cut four pitchers off their Major League roster, including starting candidates Chris Heston and Cody Martin.

One of the best pieces of news for the Mariners in spring training has been the health of the team’s five-man starting rotation — with now eight days to go until the season opens, all are healthy.

That, though, means there is now little room left in spring camp for the pitchers the Mariners brought in as starting rotation insurance. So on Sunday the Mariners sent two potential starting candidates out of their Major League camp, optioning Chris Heston to…