My next question is, is the difference between top tier Players and lower tier Players too much?
That depends on how big "you" want the gap between teams at the top and bottom is too.
The bigger the gaps for that, the bigger the gap between top teams and lower teams, and from that, less competitiveness overall all around, IMO. I'm guessing that's a big problem in getting newer players around to stick.
Everyone is entitled to their opinion
I'm not the best to argue the specific exponential curve but it seems counter-productive to "over-train" players, since they grow way to expensive to maintain, as it is, so it seems like some fine-tuning is needed. Having said that, I'm all for having 1/2 superstars (possibly 3 but with greater risks/costs) and a solid/great supporting cast to succeed. Caps and revenue should also taken into account, since it's all interconected.
Having veterans mentoring rookies could be a way to change/help training? Sponsor/Owner goals at the beginning of the season for alternative revenue? Short term money loans that bite to make short term pushes? I'm sure there's lots of options to think about but staying put as it is doesn't seem to be sustainable.
Just throwing some things around