I think he's awful at reacting to opponents. Look at him vs Real in 2nd half when Zizou changed his tactics. He didn't react at all tactically. He just kept shouting like a mad man and he brought in Lemina for no reason
Umm... Capello still coaches in 2017(granted he's a free agent right now but), and for Capello it was more ideology than anything. He wanted guys like Savicevic to run and sacrifice but the latter had other plans. Capello was stubborn in not working with Savicevic(leaving him out of 2 finals) but that's about it.
You're right in drawing parallels to Capello with Allegri in that they're defensive minded but that's where the comparisons end. The former is and always was better than the latter. I don't think defensive football is exactly "outdated"(and certainly it proved it's merits this year for Juve when they only conceded 3 goals throughout the campaign prior to the final) but in a CL Final it really never had any place and that's where you have to change your strategy and attack to secure the win.
You can't just score 1 goal and then try to defend that lead(which was Allegri's strategy he even said it on a press conference before the match) in a CL Final...certainly not against Real, you need to score more than one goal at least and keep attacking. Instead, after equalizing Juve just sat back and tried to absorb Real's attacks which was a huge mistake. Allegri's gameplan was flawed from the beginning.