I wouldn't say numerous, but he did cost us a few. As did Clichy, Lescott, Kompany, Stones more than others. On the flipside, like Kompany, Kolarov also pulled us out of losing situations. The equaliser against sunderland, the match-winning goal against Swansea in the dying seconds for 3 points, the first goal against Everton after clever play by I remembered Silva and Sterling to Kolarov. It would have been the winning goal too if not for Nasri scoring for 2-0 on the 89th. The other goals that added to our tally that more often than not gave us room to breathe in tight scoring matches. He also releases Sane at the right through a sharp diagonal pass from the left, a tactic that Pep continuously used to intentionally have Kolarov pulling in opposition players so Sane can do his explosive runs.
Kolarov is not a world class LB, above average at most. But class LBs are rare to find in the market, and until now we still haven't found one. But on the grand scheme of things, Kolarov contributed to the points table.