I've built up a picture now of the broadcast team over the Golden Age. Strikes me that Vince aimed for a team of at least 9 on-screen personalities, 3 who could do play-by-play, 3 who could do colour, 3 who could do the Mean Gene role.
The versatility of Lord Alfred Hayes seemed to cover a lot on what I've called "the C-team" since he could do the Event Centre updates and go on colour. He stays all the way until 1995 and is there much longer than you'd expect.
There are also I think two distinct lines:
1. The Ken Resnick -> Craig DeGeorge -> Sean Mooney-> Todd Pettigall line
2. The Jack Reynolds ->Rodger Kent-> Rod Trongard-> Tony Schiavone-> Jim Ross line
The Resnick line was clearly intended to be able to cover all the general duties of Gene Okerlund with any additional commentary a bonus. Recall Okerlund did commentary in 1984-7, but his chief duties were hosting All American, giving event centre updates and conducting interviews. In shoots both Resnick and DeGeorge have said they were brought in chiefly to lighten Okerlund's load. By 1986 he was presenting All American, Spotlight, TNT and doing all his usual stuff and was getting burnt out.
The Reynolds like was clearly intended as a long-term Monsoon replacement, since I've heard that Monsoon ideally just wanted to present Prime Time with Heenan and would have happily dropped Challenge or his House Show stuff. Reynold, Kent and Trongard are all searches for that replacement but it's really when Tony comes in that you can see it as they stick Tony on Challenge and one suspects it was with a view to phase Monsoon out. However, that didn't happen because he left. The eventual replacement would end up being Jim Ross.
By 1991, Mooney -- who stuck around much longer than Resnick or DeGeorge, had built enough enough experience to cover play-by-play and it seems Mooney and Hayes recorded voice overs for all the Prime Times from the debut of the new format starting February 18th 1991. You can see the January 91 Primetime shows still have different commentators. By this stage, they use a format where there's the odd match from MSG and Superstars plus Prime Time exclusive matches from TV tapings for Superstars and Challenge. It seems that by 1992, there was a Prime Time banner and someone who went live will have to explain how that worked since the exact same tapings later then have a Superstars set (with a screen). They must have taken those banners down live. The situation with different commentary teams on Prime Time -- if it was something that bothered Vince -- took at least six years to bother him. I have found one episode of Prime Time from May 11 1987 which has an absurd number of commentators (Gorilla Monsoon, Bobby Heenan, Vince McMahon, Jesse Ventura, Bruno Sammartino, Dick Graham, Ken Resnick, Lord Alfred Hayes & Ron Bass). I watched through it and it actually helped to make you think there was tons of stuff going on from many different places, so I kinda liked it. The 91-2 Prime Times with Mooney and Hayes on commentary feel much smaller.
Also watching back some of the 1990 Superstars aroud the time Piper comes in to replace Ventura and Vince is JUST INSANE on those shows. The whole product feels like it is on coke around that time!