While pitching depth remains the Rockies’ biggest question mark, another concern is who will pick up the middle relief slack, especially early on in a 60-game sprint as Colorado’s starters are getting their stamina back. That’s where right-hander Tyler Kinley could prove valuable. Kinley, acquired via waivers from Miami in the offseason, posted a 3.65 ERA in 52 games for the Marlins last year and was virtually unhittable down the stretch when he held opponents scoreless in 14 of his final 15 appearances. Via brief impressions at spring training in Scottsdale as well as at “summer camp” at Coors Field this week, manager Bud Black believes the 29-year-old fourth-year pro has a chance to be a bullpen pillar. “Seeing him up close, he’s got a firm fastball (at about 95 mph) and a really hard slider in the high 80s, that will touch 90 with some good depth to it,” Black said.