Great form in 18/19? He was poor the entire season (it started with his terrible showing at the World Cup before the season) before he, as you said, completely collapsed for the last month or two. Any average PL keeper for the end of that season and we should have made the top four, as having DDG was pretty much giving the opposition a one goal head-start in every match and directly cost us numerous matches. Maybe saying single-handedly was harsh, but he was easily the most at fault.
DDG made himself as small as possible and tried to avoid contact (after being in a poor position in the first place) for the goal that ultimately knocked us out of the CL last season. He did an almost identical thing a month or so later in the league too, so it's not like it was a one-off.
These were huge, constant mistakes over the course of three seasons, seemingly even more often in the big matches, on top of him being significantly below average in basically everything other than shot-stopping. It's quite unbelievable that he made it to this season as our first choice (but then again there's a fair chance Henderson would have started the season as first choice if it wasn't for having a bad case of Covid). Yes, he managed to get his shot-stopping abilities back this season, but how long are we going to ride just on that? And how long until he drops off again?
He wasn’t poor the entire season, by any means. His form collapsed at the end of the season and he made more mistakes in that period during his entire career with us combined, shit happens and we were overall shit that season.
The goal that ultimately knocked us out, Jesus, they were 3 goals up when we got a lucky penalty and a deflection to make it 3-2 with 8 minutes to go, don’t be silly. Neither goals were more ultimate than the other.
Maybe Henderson would have started, maybe he wouldn’t have, he didn’t and overall De Gea has performed well this season.
In terms of riding on it, again, this really isn’t complicated by any measure whatsoever. The fact remains obvious, we have bigger gaps to cover in our squad at the moment. Would you prefer it if our central midfield remains as shit as it is, and how it impacts our ability to attack and defend, to make it our top priority to bring in a new goalkeeper? Should we wait with signing a new striker perhaps, or how about ignoring the massive problem at right back.
Some common sense would be highly appreciated. If the next manager prefers to play Henderson, he will.