Based on his time at Dortmund I wouldn't say he's a big game specialist.
CL/EL:
13/14: he was the first to get subbed off in Madrid and then wasted all his chances in the return leg, when Dortmund were dominating them.
14/15: he didn't really stand out in any CL games and was fairly anonymous against Juventus.
15/16: I won't count anything before the knock-out matches since no one really took them seriously anyway. Against Porto and Spurs he had four really good matches, the team in general stomped both of them pretty much.
Against Liverpool he was rather anonymous in both matches (aside from scoring a tap in).
Generally speaking his record here is very mediocre, especially in the CL.
BL/Cup:
If we look at the matches vs Bayern he was rather anonymous in them (bar the 0:3 victory in Munich in 14/15), in the last cup final he also refused to take a penalty, so two CBs had to step up.
Thinking about it he really seems more like a follower than a leader. Not someone to step up or bail you out when things aren't going your way.