Zack Wheeler is still “close” to joining the Mets, but his performance yesterday for Triple-A Las Vegas did little to bolster his case. The stud right-hander was removed against Salt Lake after four innings in which he surrendered five runs, three earned, on four hits and three walks with four strikeouts. Wheeler also gave up two home runs in the no-decision. “Zack’s command was off today,” Las Vegas manager Wally Backman said. “We had him on a short pitch count [80 pitches] just to be cautious due to the fact he missed that one start and had 10 days off.” But a high-ranking club official said he doubts Wheeler’s lackluster performance will translate into an additional stay in the minors. The official said Wheeler is expected to be promoted after making 1-2 more starts for Las Vegas. “He’s on track,” the official said. Wheeler peaked at 99 mph on the radar gun yesterday, with “lots of 97s,” according to Backman. Wheeler is 3-1 with a 4.13 ERA in 10 starts for Las Vegas. He has made two appearances since missing a scheduled start because of soreness in the AC joint in his right shoulder.