I'm not terribly familiar with Wawrinka's prime (didn't watch tennis from 12-17) but I will say he strikes me as someone who seized opportunities given to him much more so than Roddick did.
Roddick, due to whatever reason (poor clutch play or lack of confidence/self belief or mental block causing him to tighten up), very rarely seized opportunities given to him in big moments/matches/tournaments. I can only think of 3 GS tournaments in his career in his career where I'd call him kinda clutch and opportunistic and those are 03 AO/USO and 09 Wimbly. And of course even there, he clowned the first set vs Nalby (had 6 BPs in one game that he couldn't convert; made UEs on most of them) and the second set TB vs Fed.
Some other chances he blew in GS matches include (I won't bother mentioning his pathetic out of form losses):
- 03 Wimbly SF first set. Had SP and netted a routine inside-out FH. Now, there's no guarantee Roddick even wins the point, but I'd favor him to do so as Roddick in 03 was generally successful with going to Fed's BH with his I/O FH (gaining control of the rally or potentially forcing an error). Had he won the first set, again, given the level Fed displayed (arguably his GOAT grass match), he would've won in 4 sets but Roddick would've had more confidence after winning the opening set and likely puts up a more respectable performance.
- 04 AO QF. Minor one but Roddick had played an excellent return game to force 2 BPs when Safin was serving for the match. On the second BP, Roddick netted a simple FH return on an absolute sitter of a Safin second serve. Again, no guarantee Roddick even wins the point had the return landed in and not sure if beats Safin either. Either way, this one could be considered irrelevant as Roddick had no shot of winning this tournament.
- 04 Wimbly F. Dip early in the second set, blew/failed to convert on some BPs in the 4th set (made UEs). Golden opportunity.
- 04 USO QF. Won 24 more points overall but blew some big BPs and was clearly tight serving to stay in the match at the end. Made a DF in each of the three games he got broken in. Not really a winnable tournament but a horrific loss, especially as this was the loss that made him start making changes to his game.
- 05 AO SF. 2 consecutive DFs when up a break in the third set to get broken back. He had no business losing this set. Had he gone up two sets to one, he's in the driver's seat. I have a lot of respect for Hewitt's run so I certainly wouldn't count him out down 2-1. But I give Roddick a 60 percent chance of winning the match at that point. And little chance Roddick ever melts down after a two sets to one lead like he actually ended up doing in the fourth set. And in the potential final, Roddick actually matched up quite well with Safin. Straight setted him at 04 TMC and beat him on a fast indoor court at Bangkok in fall 04. These two wins were during the best run of Safin's career and Safin was a far superior indoor player to Roddick too. I don't mind favoring Safin in a potential final but Roddick would've absolutely had a shot. So again, this was a good chance with Federer out that he kinda blew.
- 07 Wimbly QF. Up two sets and a break to Gasquet and blew it. Not a winnable tournament but a pathetic meltdown.
- 08 USO QF. Served for the fourth set, made 2 consecutive DFs. Made a dumb decision to drop shot at 5 all in the TB when he was dictating the rally. Again, it's debatable if he would've even won the 5th set but my point at large is to show him failing to seize opportunities due to his own doing.
- 09 Wimbly F. Second set TB. No guarantee he wins the match up two sets to zero (same guy who blew two sets and a break lead to Gasquet in his prime) but he would've put himself in a much more commanding position.
Again, most of these instances, there's no guarantee Roddick would've gone on to win the point/set/match/tournament. But my point on a larger scale is that Roddick rarely capitalized on opportunities presented to him and often tightened up or made bad decisions or errors in such moments that led to his downfall. Not sure if same could be said about Wawrinka.