Say this for the Giants. If a player with any degree of value is available, they’ll have interest. With an abundance of roster openings, they aren’t quick to rule anybody out. In other words, it’s not all about Giancarlo Stanton. It can be anyone from Eduardo Nuñez, who played in San Francisco before his July trade to Boston, to J.D. Martinez, who actually had a better home run rate than Stanton. Two industry sources said the Giants have had discussions on Martinez, the most potent hitter on the free-agent market whose contract would be less than Stanton’s and with fewer years. That’s not to say Martinez is on the front burner, but it’s part of casting a wide net, a phrase the Giants like to use. Neither the Giants nor Martinez’s agent, Scott Boras, would comment on the team’s interest in the outfielder, but general manager Bobby Evans said Wednesday, “The doors aren’t closing on options. We want to explore every scenario that works for us or comes our way in a deal.” Like Stanton, Martinez would greatly benefit the power-deficient Giants. While Stanton hit 59 homers in 159 games, Martinez hit 45 in 119 — including 29 in 62 once he got to the Diamondbacks. That equates to one homer every 10.1 at-bats for Stanton, one per 9.6 for Martinez.