I don't believe the FBI is any more or less corrupt now than then. But any corruption today is under Trump's watch. It's his FBI director. It's his attorney general and assistant attorney general. He picked them and got them through the approval process.
In short, Trump was boxed in by a poltical nomination process which, again, was not D versus R, but reformers versus good old boys. The reformers lost. Same with Wray who was also a compromise with the good old boys.
The lack of significant FBI reform Russian collusion witch hunt is technically Trump's fault but I was of the opinion (and still am) that MAGA is much more important and that Trump had to (and actually has) made great progress while mainly ignoring that ridiculously corrupt and meaningless investigation. It is purely a political question and knowledgeable Americans support Trump.