It seems you are saying the old Chrysler Corporation would have done just fine without Fiat or Sergio, but I don't agree about the part without Sergio.
Perhaps it sounds that way, but it's not really what I intended... I read your post this morning before the drive in and thought about how to answer that.
What the company needed in late 1978, and then in late 2009, was strong leadership focused on fixing the core business. The pieces existed in each case. Maybe it's that crisis managers become addicted to milking the life out of products. A good skill when the money isn't there, but initial success breeds overconfidence.
Iacocca brought financial discipline and cleaned up manufacturing quality, and hit a few home runs. He then relied too long and too hard on the K-platform and became distracted with non-core expansions.
Marchione did the same on financials and manufacturing, but missed on a few key products and then starved the golden goose and become distracted by Alfa.
One key difference was Iacocca, a larger-than-life personality, gave the impression that he was absolutely committed to Chrysler's success and managers drove that message down to the last entry-level floor-sweeper. He obviously knew the company was a train wreck when he arrived, but never gave that impression publicaly.
Marchione perhaps of equal intellectual talent, was aloof and sent the opposite message... Our long-term survival relies upon outsiders. Merging with GM or some other company. He was publicly critical of his own company in an information age that doesn't tolerate such missteps.
Thus Marchione never created the "esprit de corp" that made people go the extra mile, or
desire to join the team.
(BTW there is a super-obvious political parallel here, but I'll stay on target)
Then there was the arrogance of thinking you were going to "retrain" the American driver to love 1.4L stick shifts, because that's what Fiat had in their arsenal... The opposite of what the Japanese did to sell in this market. I believe it may have been the Agnelli's pushing Alfa, but it should have been monitized when VW wanted it. They're not even good sellers in Europe, let alone the US or Asia. Read some of the early reviews on the Gulia; terrible.
So it's not that I disagree about him saving the company, it's that I believ others could have done as well, and even better. For those reasons, I'll give his tenure a solid "C".