I read the same thing.
Burr actually was really good in the roll. I personally think Perry Mason was the best show ever. Della Street was a doll. I read also that Orson Wells thought Ray Collins (Lt. Tragg) was the best actor he ever knew.
Mannix was one of the better old TV shows.
PM is definitely a gold standard program. I liked William Hopper aka Paul Drake.
Burr did some radio drama, Fort Laramie. It’s rather good.
I’ve got a few Mannix DVDs around, maybe they’ll get some play this weekend.
The casting on Perry Mason could have been this.
Actually William Hopper, who played Paul Drake was considered for Perry Mason and Raymond Burr for Paul Drake.
In the end they switched them.