Here are some numbers - all drafted goalies (and undrafted goalies who played a game) since 2000:
Rnd | Drafted | Wins | SV% | Success | Success Rate |
1 | 32 | 3732 | .898 | 16 | 50% |
2 | 72 | 3090 | .904 | 23 | 32% |
3 | 86 | 2843 | .883 | 18 | 21% |
4 | 80 | 1494 | .892 | 10 | 13% |
5 | 108 | 1107 | .910 | 8 | 7% |
6 | 104 | 797 | .909 | 8 | 8% |
7 | 90 | 1233 | .891 | 6 | 7% |
8 | 17 | 490 | .853 | 2 | 12% |
9 | 13 | 574 | .912 | 2 | 15% |
Undrafted | 31 | 2794 | .905 | 20 | 65% |
Success for the purposes of this table is defined as 100 games played, so the bar isn't too high (if you set it at 200 games, the R1 success rate drops from 50% to 34%).
The Undrafted success rate is going to be skewed because the set of undrafted goalies who never played in the NHL includes a lot of players (including Buffdog?)...so there's quite a selection bias there.
Here is a chart of the number of goalies drafted in each round and the aggregate SV% of that round's goalies:
View attachment 1042799
They stopped drafting after round 7 in 2005, so it's a small sample.
The scatter plot of all goalies drafted since 2000 doesn't show much in the way of a strong trend in terms of SV%.
View attachment 1042801