I am not defending JV tactics, i am just saying they already know what tactics doesn't work. The tactics that doesn't work, against Pogačar, is controlling the race and giving Pogačar a free ride. If they would repeat such tactics, that would be stupid.
There is no ITT remaining. Rogla was as strong as Pogačar on the stage 3 climb, and Pogačar would have needed to drop him by a decent amount to win the race. Hell, Jumbo could let a breakaway go to take time bonuses out of the equation, and make Pogačar need twice as much too.
If they would do that today, race to the line, they would lost seconds. Based on the current form, Pogačar is a bit punchier, bunch sprint.
They can still let a move go. McNulty didn't initiate that move. They could still let people who are over a minute back like Buchmann, Izagirre, Chaves, Carapaz go. They'll take the bonus seconds out of it, and they aren't teammates of Pogačar so they don't have the opportunity to play the 1-2 card. And if they aren't going, then even if he loses a few seconds to Pogačar at the line, Rogla will still lead the race rather than being 20+ seconds down. At the very least they could have limited the timeloss - it's not like they went super hard, seeing as Bevin and Knox managed to ride away fairly easily and keep the group at bay too.
And what did UAE gain today? Pogačar is the captain and he gained nothing today, more of the opposite.
They gained the leader's jersey, a second realistic bullet in their gun, and a headstart of over 20 seconds. Just because Pogačar is the captain doesn't mean he's the only one allowed to gain time. Carapaz won the Giro like this, in fact. Wasn't it Jumbo that let him up the road then, too? Can't recall. Might have been Nibali's guys at Trek instead - Polanc had the maglia rosa from a break at that point. And now, UAE are in the position where they know Roglič has to gain a specific amount of time - and it's not inconsiderable, so time bonuses might be important - so UAE might do as I said Jumbo could have done and let a break go, and say to Jumbo-Visma, if you want those bonus seconds, you've got to do the chasing, which increases the chances of Roglič being isolated at the point where he needs to set up his all important attack.
McNulty could surprise, but then again if JV underestimated him and he can keep up with elite climbers, then he deserves it. Is McNulty really considered to be a bigger threat, compared to Pogačar? Stage 3 said no.
The finishing climb on Saturday is less steep than stage 3. The climb that's like stage 3 is 40km from home. The finishing climb is more like today's last climb, where McNulty was absolutely fine. It's also a short stage. And now, rather than Roglič getting to pick and choose whose attacks he follows, he has no choice: he's got to make an attack himself. Because this morning, Jumbo needed to do nothing - if everything stayed as is, they would win. Now, if everything stays as is, they lose. And the reason for that is that they committed tactical harakiri.
If they win this race, it's not because dropping the jersey today was a tactical masterstroke, it's because Roglič was strong enough to overcome the tactical errors of his team. I actually like Rogla. But the thing that went wrong when they employed "tactic that was proven to fail" wasn't holding the jersey and racing from in front. In fact, letting a move like this escape in stage 8 instead of capitalising on their strength was exactly what caused that tactic to fail. And if my memory is correct and it was Jumbo that let Carapaz go on stage 14 in the 2019 Giro, then isn't that strategy - the exact one they employed today in fact - a strategy which was proven to fail too?