Assuming injuries and age take their toll have nothing to do with professionalism of our players.
We have some studs- no doubt, and that's what makes it hard to give up on 2020. You can't get much better than Betts, Devers, Bogey, JD and a healthy Sale, but this team has precious little else, except wings and prayers or rebounds, miracle recoveries and more.
Look at the 40 man roster. I've not seen a more shallower roster since last century. We have 20+ players that are not expected to be much help in 2020. Sure, some will and some will surprise, but some we expect to contribute may decline as well.
40 Man Roster 2020
Only 8 pretty sure bets (maybe 7, if not counting Sale):
Betts
Devers
Bogey
ERod
JD
Sale (a big question mark)
Workman
Beni
12 Not Sure to be very productive
Price
Eovaldi
Barnes
Vaz
JBJ
Walden
Taylor
Perez
Peraza
D Hernandez
Chavis
Plawecki
That's only 20 players total!!!
4 Future Help, at best
Dalbec
Chatham
M Wilson
Y Abar
Maybe we get 20-21 total. That's half the 40 man roster!
16 Could DFA or trade for scraps (or injured) and I wouldn't blink an eye
Hembree
Pedey
Velazquez
Lin
Brasier
Brewer
Reyes
Weber
Shawaryn
Osich
K Hart
J Arauz (rule 5)
C Mazza
A Brice
J Springs
M Hall