That is the case for conventional cooking, but according to one of the leaders in sous vide research, Dr. Douglas Baldwin, "This tenderizing is caused by weakening of connective tissue and proteolytic enzymes decreasing myofibrillar tensile strength. Indeed, collagen begins to dissolve into gelatin above 122°F to 131°F (50°C to 55°C) (Neklyudov, 2003; This, 2006)."
That is why you can sous vide a rack of ribs for 72 hours at 135F and have them bite off the bone tender yet cooked to medium rare.
The real question is, did they taste any better than if you would have just smoked them all the way?
Was it worth all the extra time and effort? Or, were you fixing something that wasn't broken?
The end result was not worth the effort. As is the case for most things done for the first time, if i were to try again, I will tweak some things to try to get better result.