Seems to me that these are two Different Topics.Not for me as I really believe it depends upon the actual player, his position and his situation with the key being how easy it would be to replace said player (Admittedly that is easier for some organizations than others).
That's why I said that most solid veterans are also JAG.
For example. Ernest Jones was a solid LB. He was easily replaced by JAG Nate Landman.
IMO, it's far more difficult with QBs and far easier with other positions like WRs. Don't get me wrong, talent is important at WR. But a lesser talented WR who is merely on the same page with a good/great QB can still put up numbers do wonders on offense.
One is simply player-evaluation-opinions ... which vary. One person may view a player as a Solid Veteran, while someone else may view that same player as a JAG. Just varying opinions that are subject to debate.
The second topic is one of objective classification of the terms Solid Veteran vs. Just-a-Guy.
To describe a player as a Solid Veteran is to state that he is More-than, or Better-than Just-a-Guy.
The terms are simply not synonymous. I just don't see that as debatable.