Not just Sarri but even Gasperini.
I can't understand what Inzaghi has done to satisfy the high standards on here. He hasn't even experienced the UCL. In fact, we make fun of Sarri only winning the Europa League but Inzaghi managed to lose 4 times this year to Celtic, Cluj and Rennes.
Before this year, his highest finish in Italy was 5th and Gasperini has already done that easily with Atalanta and is in the UCL knockouts. And people make fun of Sarri finishing 2nd with 91 points.
We are quite literally talking about a 24 match span, I think. As I don't see anything before this year as noteworthy. And in Europe, it's laughable. I don't see anything in his profile that would suggest he's ready for Juventus. If Sarri did not meet the standard (which might be correct) then I don't see how Inzaghi meets it, that's all I'm saying.
I also don't think he was particularly smart with SMS, playing him so deep in the past. Doesn't really take a rocket scientist to figure that one out.
Not sure about how much you've followed Lazio in recent years but this years success hasn't come out of the blue. They've been playing good football in previous years too, but have been desperately inconsistent. This year something simply clicked for them on the mental side to be able to put these performances on more regular basis.
Hiring a coach is about fit and not necessarily about their past achievements, this is especially true when looking at young coaches, case in point Conte was even more inexperienced at this level when he came here. Lippi hadn't won a trophy before Juve either and his record was pretty mediocre, Trap's only experience at top level was a short caretaker stint at Milan. By fit I mean having the right personality and having the ability to play football that actually suits the players you have.
No one can know whether a coach is ready for Juve before that coach actually coaches here. No one can promise that a coach can transfer his success from another club to this Juve. Just look at Sarri, it's clear that for whatever reason Napoli was almost a perfect fit for him and he hasn't been able to replicate the football they played in any of his following two clubs (yet). We need a coach that is a good fit for this Juve, whether that is Inzaghi, Sarri or someone else I don't know, but I definitely don't agree with your overly simplistic way of evaluating Inzaghi's fit for a role at Juve.
Also SMS is playing deeper now than in the past and he is perfectly capable of fulfilling that role nowadays.