well, I'm still around

Rebel fighters had to enter the trench at a specific point on their approach to the exhaust port that wasn't heavily covered with turbo laser batteries. Namely toward the southern most point of the trench. Turbo laser fire was much too dense for them to effectively approach the port from a vertical descent into it. They would have been ripped to shreds. With fewer turbo laser batteries in the trench, the small, agile rebel fighters would have had a fairly easy approach to the port. That's why it was necessary for Imperial TIEs to give chase to effectively eliminate them. To complicate things even more, there was a tremendous amount of jamming and counter jamming occuring during the assault.

The Y-wing has superior targeting capability to the X-wing. Partly due to it's secondary role as a light bomber. When the the Y-wing's targeting cpu and short range sensor systems are used in tandem with the long range sensors, it offers slightly better targeting accuracy than the X-wing. One reason why Y-wings were the primary attack craft at the Battle of Yavin. Dutch (Gold Leader), Tiree (Gold Two) and Pops (Gold Five) were able to identify, mark and lock the exhaust port in their targeting computers on their approach while Garvin, Luke and their wingmen were not. Garvin's torpedo volley had just barely missed the exhaust port. That being the case, it is evident that Dutch would have had no problem hitting the port had he gotten in range. Unfortunately he and his wingmen mad some very bad decisions on their approach. For one thing they had transfered all power to the deflector shield systems, effectively robbing a major portion of energy from the engines and vastly reducing their potential max speed. In addition, Dutch was unable to take effective evasive action without risking colliding with Pops due to him crowding his flight path. Both of them were killed as a result. What they should have done is transfer all power to the engines, increase speed full throttle and angle their deflector shields double back. Tiree and Pops should have stayed back far enough to cover him and have their ion cannons fixed dead aft for any possible pursuers. Essentially what Luke, Biggs and Wedge did, which was only logical. An even better solution would be to have Tiree and Pops piloting BTL-S3 Y-wings (two seater model) with two additional rebel pilots as gunners.