There are a few other reasons to tuck too.
1- It is easier to keep the elbows and forearms directly UNDER the bar - vip for keeping power transfer directly into the bar from the forearms and grip. See 4.
2- Benching to your stomach while it’s pushed out with air shortens stroke tremendously and combined with pinching the blades you can take serious inches off the press. This requires a major tuck.
3- Tuck allows the lats to catch the weight at the touch and thus begin the ascent. The more of a flair there is, the more the smaller and weaker front delts try to take the load. Trust me you want the lats to catch the weight.
4 - This has made the biggest difference for me and is a personal feeling - the more big “body parts” I can get behind the lift, (in this case under the lift to push) the better and stronger I am. This is why we try not to bend too far in front of the toes in the squat, or let the bar get too far out in front of the deadlift. We want everything under the bar so all of it can push with synergy in the squat. We want to pull the bar into our groin in the deadlift while simultaneously shooting our hips through.
Same with the bench. With a major tuck in both our elbows and feet, along with putting “the shoulders in our pants pockets,” everything gets under the bar as much as possible and there is a line of power transfer from the feet and through the lats, abs, stomach, arms and finally the bar. This is how and why leg drive rules the roost for the bench - it all begins there and shoots through and moves the bar.[/quote]
Good stuff. To point 4, in that Louie Simmons vid I mentioned above AJ Roberts says he’s seen someone benching properly blow out their quad because they are driving so hard, but he’s never seen someone who benches properly injure their shoulder.
OP, I think one last big thing Dave Tate has mentioned a couple times (and probably in one of these videos) is that you can really only fix one thing at a time if the motor pattern is already engrained (as is the case for almost everyone by the time they start trying to fix technique on the bench).
I try to go into each bench session with one thing to really focus on – be it keeping the weight on my traps, tucking my elbows, pulling the bar apart, whatever I think could definitely need improvement. We want to build towards having everything moving properly, but it really has to be one step at a time.