He looked like a pretty big liability last week times.
He wasn't on long enough to be a liability last week. Twelve tackles, none missed, one ineffective.
He's been average so far, certainly due to making too many tackles. It's not his job, much like Nathan Brown. This year Evans has missed 5 tackles from 61 attempts (92%), and attempted 0.68 tackles per minute. That is very high. We would prefer his defensive work to be below 0.5 tackles per minute. That will allow him to make more runs.
Here's some more middle forwards for comparison:
Alvaro: 3 missed from 108 attempts (97%), 0.81 attempts per minute (NRL gold standard)
King: 10 from 114 (91%), 0.60 per minute
Brown: 2 from 88 (98%), 0.45 per minute
Mannah: 6 from 70 (94%), 0.57 per minute
Bromwich: 4 from 93 (96%), 0.39 per minute
Asofa-Solomona: 2 from 62 (97%), 0.31 per minute
Taumalolo: 7 from 99 (93%), 0.41 per minute
McLean: 2 from 74 (97%), 0.36 per minute
Scott: 11 from 78 (86%), 0.39 per minute (a considerable factor in why the Cowboys aren't going so well this year, and why he was probably no great loss last year)
De Belin: 5 from 99 (95%), 0.39 per minute
Vaughan FFS: 2 from 101 (98%), 0.44 per minute
Paulo: 2 from 71 (97%), 0.59 per minute (much higher than normal, which explains why they're winless in 2018)
Boyd: 0 from 75 (100%), 0.40 per minute
Napa: 7 from 87 (92%), 0.38 per minute
JWH: 3 from 83 (96%), 0.70 per minute
https://www.foxsports.com.au/nrl/nrl-premiership/stats/