Having slept on it, three things occur to me today.
Firstly, many upsets involve a host of scarcely believable missed chances for the favourites, or incredible saves by the underdog goalie, or a once-in-a-lifetime goal, and so on. Hence, it is often the case that if the same game were replayed 10 times in precisely the same way, the favourites win nine of them. That isn't what happened yesterday. If that same game was replayed in precisely the same way 10 times, I would fancy Macclesfield to win it 6 or 7 times. They created as many chances as we did. Their goalie was no busier than ours.
Secondly, whilst the manager must of course take his share of the blame, yesterday is largely down to the players. Glasner has drilled in a defensive, cautionary approach which relies on attacking either on the break or in fits and spurts, always without the defensive shape of the team being disrupted. For example: Our midfeilders almost never get forward. Our wing backs usually join the atack after it is underway as space opens up, and rarley start high and wide, meaning we have limited width in our attacking play. We usually start with five defenders. All of that gives us our best chance of doing well in the league, and was a huge part of winning the cup, but it isn't suited to playing European minnows and other underdogs.
He did change the shape yesterday (for the first time ever?) but the players aren't used to a Plan B and it didn't really help. Even so, Glasner is entitled to think that the team he put out, in the usual 343, could control the game wholly and find ways to score. It wasn't Glasner who lost a header on a set piece (again). Glasner didn't f*** up a headed clearance, or his goalkeeping footwork for the second goal. He didn't constantly get the ball stuck under his feet, or misplace passes, or take absolutely ages to move the ball sideways and backwards. I don't see that his system, tactics, or selection make any of these things more likely. To me, he was let down more than he was responsible.
Thirdly, its done now. If I had been offered a deal whereby Palace win the FA Cup then the Charity Shield against Man City and Liverpool respectively, but then get knocked out the following year by Macclesfield, I would have taken it 1000 times over. In fact, its so Palace as to be almost perfect.