I think a better way to put it is "The German navy was outweighted by the Allied Navy".
To the Raeder issue, we really don't want a carrier attitude admiral since it carriers actually are waste of resource for the Nazi. So a BB admiral may not be such a bad thing. But if we have POD that puts naval aviation under the Navy, would Raeder not have embraced the funding? If planning the BoB, not Goering, would Raeder not have went for the ports first? If there was quality staff planning for a naval war with the UK, would Raeder not have executed the plan?
As to Donitz, which assumptions do you see as the problem?
Now as to how I would write this type of ATL, I would put the main character (the POD) in the first 100 or maybe first 20 Nazis. He would be a trusted, and original associate of Hitler, and would make better decisions. It is the same path I would use to boost food production, or to fix most other single weaknesses of the Nazis.
That was also a factor, but the German navy made heaps of mistakes and were outplayed by the Allies. Big mistake: Plan Z, pushed by Admiral Raedar. In intel they were screwed by SigInt issues, Doentiz pushing for war with the US, and getting played on things like the Metox receiver. The KM's use of radar was extremely limited, including hiding their development from all the other services and running their own research program independent of the others.
Raeder demanded carriers BTW:
https://en.wikipedia.org/wiki/Graf_Zeppelin-class_aircraft_carrier
The problem was he really didn't know what to do with naval aviation and demanded things like a dive bombing Do217, which delayed the design thanks to wasting effort trying to make it into something that wasn't really possible (long range naval dive bomber). Despite having the patent for the Italian air deployed naval torpedo pre-war the German navy never used it and instead produced a bunch of defective torpedoes, both regular and air deployed, which had issues beyond just the magnetic trigger.
Doenitz wanted war with the US, tried to centralize all Uboat operations and got them sunk (
https://people.eecs.berkeley.edu/~wkahan/BlaUboat.pdf), and failed to develop certain technologies earlier enough to get use out of them...plus there was the torpedo issue he ignored for nearly a year.
Getting rid of Goering in 1936 instead of having Walter Wever die in a plane crash and then getting Fritz Todt leading the 4 Year Program would help a lot...but the issue is that without Goering there is a huge problem with the diplomatic side of the run up to the war that probably leads to war early and in a far less favorable situation for Germany, given that Goering actually helped moderate Hitler and sweet talk the British, who were convinced he was a moderate of their class that they could trust.