You can't say he shouldn't have played, we have a cup keeper, that's how we operate and how we will always operate. Pep is a man of Honour and will never screw his number 2 keeper over, ever. Liverpool did, they benefitted today but their backup keeper won't hang around long with that kind of treatment.
The problem is either, Pep has asked a player that isn't Ederson and isn't capable of being Ederson to be Ederson, against the best pressing team we could possibly face too no less, In which case its on Pep for not adapting our game knowing a player isn't capable of doing the usual things we do. Or, Steffen has taken it upon himself to try and imitate Ederson and doesn't recognise his limitations, in which case its on him to understand what he can and can't do and the mistakes are entirely on him.
None of us have ears inside the dressing room so we won't know which is the case but simply saying Pep should have played Ederson is just a garbage comment, that's never happening under him.
As for claims about him not being good enough, what are your expectations of our backup keeper? Everytime we concede a goal when Edersons in net, there's a dozen posts claiming Steffens a better shotstopper, and now he's not fit to wear the backup shirt? Who is good enough? Any backup keeper you can suggest that's better than him isn't content at their club as a backup. Our backup keeper is always going to be especially susceptible to messing up badly in our style, it doesn't excuse major fuck ups like his today, nothing does but he fits the bill, he's adequate he's just had a complete howler.