I don't really remember Forney because I was still very young when he was doing play-by-play but my Dad always told me about how great he was.
He said that Forney painted such a vivid picture of what was happening that you could almost see the game in your mind's eye.
Listening to Eli for me was like watching the game with a Blindfold over my eyes with someone talking about everything but the most relevant information.
I'd rather listen to Beth Mowins with RGIII and Danielson than Eli.
That is a little harsh about Eli. In his prime, he was good IMHO. He was never great at painting a picture as Forney was (I agree with your dad) but even Forney wasn't as good at the end of his career.
However, I think part of the problem is that we all used to be better at imagining things in our mind with not as much description needed as we need now. Now we have video screens everywhere with every type of content imaginable at our fingertips. Years ago that was not the case so we used our imaginations more so when someone described something they probably didn't have to work as hard for us to be able to imagine what they were saying. Now we don't have to use our imaginations as much so when we listen to something we have to been told in much greater detail. That doesn't excuse going long periods of time during a game of not giving the score, down, distance, etc. but at the same time if a person was listening to a game in the 70's they probably had that information in their minds because they were following along more closely. Now we're distracted by any and everything and we don't store information like we used to. I'm just as guilty as anyone of this. Before we had every bit of information available at our fingertips, I could remember many, many things that I can't remember nearly as well anymore.
But specifically about Eli, he always had a bad habit of making a play seem different than it was in reality. He would get really excited as if a player had made a long run when in reality it would only be 1-2 yards and vice versa, he could make a 5-7 yard run seem like a 1-2 yard run. His voice and ability to speak were always topnotch but I think he over-relied on his natural ability and never quite mastered the actual craft of calling a ballgame accurately.