Most NHL goalies' goals against end up lining up pretty evenly with their expected goals against these days. There are always a some outliers (positive and negative), and Shesterkin may end up being one of the positives over the next several years... but it's still tough to justify breaking the bank on that position, imo. Would rather have a 4-5 million dollar goalie with an extra 6-7 million spent on the defense.
But, as we know, when free agency rolls around, GMs don't really give a shit about anything anymore. It'd be great for the Rangers if nobody was willing to pay Shesterkin what he wanted, but somebody inevitably would. If nothing else it benefits the Rangers (imo) that he apparently only wants a 4-5 year deal (presumably because he believes the cap will go up enough for him to get another raise on his next deal?) so I dunno... at least if you're gonna have a goalie be your highest cap hit it's better to have it be 4 years instead of 8.