I think everyone uses whatever criteria they want. Personally I'm essentially applying an expected value equation where value is determined by "how much would I have to trade for them/pay them as a UFA to acquire this player). Obviously I'm not actually crunching numbers but it's just
Expected value = Sum( P(x) * x) for all x where x is their value in each career state and P(x) is the probability of occupying that state.
So to breakdown why I chose Berggren over Cossa, my evaluation of a goalie's value is very low unless they're an all star and I don't view that as particularly likely. I'll give an approximate breakdown, but it's more for a relative comparison than an absolute one. It's very hard to say what the odds of either becoming an all star or the value of an all star exactly-I'm sure that I'm a little optimistic in general but you get the idea
Cossa:
All star: P ~ 5% x ~ 120
Consistent 55+ game starter: P ~ 10%, x ~50
Tandem goalie: P ~35%, x~ 10
Backup: P~ 30%, x~1
Bust: P~ 20%, x~ 0
Which would give an expected value of 14.8 arbitrary value points
Whereas for Berggren I break it down like
All star: P~5%, x ~ 80
1W: P~ 20%, x~ 50
2W: P~35%, x~20
3W: P~30%, x~5
4W/Bust: P~ 10%, x~0
Which would then come to 22.5 arbitrary value points.
Honestly while I view Veleno and Johansson as way less likely to be all stars or even 1st liners than Berggren, I think they'd have about 15-20 value points for me so I'm taking them above Cossa too.