Bartolo Colon kept a low profile for the Mets in spring training, but won’t be afforded such a luxury now. The organization’s big offseason pitching acquisition — he was signed to a two-year contract worth $20 million in December to help fill the void created by Matt Harvey’s absence — will make his Mets debut Wednesday night against the Nationals at Citi Field. The 40-year-old Colon didn’t waste time making an impression on teammates in spring training. “He is a fearless pitcher who understands the pitching aspect of the game,” catcher Travis d’Arnaud said. “More importantly, he is a great teammate.” Colon went 18-6 with a 2.65 ERA in 30 starts for the Athletics last season, after receiving a 50-game suspension in 2012 for testing positive for testosterone, a banned performance enhancing drug. Colon had a delayed start to the Grapefruit League season after incurring soreness in his calf. But the right-hander still made three major-league exhibition starts in which he went 1-1 with a 5.28 ERA. Manager Terry Collins used Colon in a minor-league exhibition on Thursday rather than expose him to the Nationals in a Grapefruit League game just six days before he would face them.