For lineman and less mobile QBs I have no idea why the surgery can not wait at least until after the season. Depending upon pain levels and ability to wear a brace.
However, there are a number of reasons to just have the surgery if you are relying on cutting.
1. It is not often that a knee has an isolated ACL tear only especially in high impact high velocity sport like football. A lot of ACL tears has meniscus tears or MCL tears as well.
2. If there is no support given by the ligament, so muscle needs to work twice as hard a stabilizer. That takes time to have your quads and hamstrings learn how to fire to completely stabilize the joint. I think Hines Ward has to work twice as hard in the off season to keep his lower body not only strong, but he must work on proprioception everyday even during the season. Most athletes are not willing to work that hard on a daily routine. From what I remember, he didn't even know that he lacked one. Is that possible?
3. Braces are bulky and slow down an athlete at such a high level. There are times that the brace is not effective at all. I don't think the article implies that a player should just strap it up and play for two years. I think the research talks about those that rehab without surgery and the process takes about as much time as it does for a guy with surgery to get healthy enough to be back at a high level, not healthy enough just to play.
4. The chances of your knee buckling again on a route greatly increases. When it happens again you have no resistance from the femur sliding along the tibia, so the chance of damaging the other structures greatly increase. If this is ignored the chances of needing serious microfracture surgery increases and would either make you sit out longer or can end your career right there.
5. Psychologically athletes are different, but i would say players without the ACL and know the risks involved hold something back compared to when they return with a reconstructed ACL.