Even though Vas has not been very good this year, your league does not track goalie percentages (GAA, and SV%) so Vas' weakness this year isn't going to hurt you at all. So far he has no shutouts despite playing just under half the games he played last season. Last two seasons he had 6 and 8. By the numbers alone, he should have 2-4 already. I think the bolts will make the playoffs (which means they will win more in the remainder of the season), but I am not sure Vas will be the reason. His has been too inconsistent.
For what it is worth, I traded Vas away last week and a few folks here thought I made a mistake.. By your scoring, Vas has 65 points and Ullmark 55. If Vas can start to get shutouts at the pace he did over the last two seasons, then you should expect 3-5 for the remainder of the year. If he does this, then I think he would be a huge upgrade over Ullmark (to the tune of 45+ points) since I think he will get 5+ more wins than him over the remainder of the year.
In terms of skaters:
Huberdeau > Tkachuk = Karlsson > Giroux
The question is how much better is Huberdeau than Tkachuk and Karlsson and how much better are they than Giroux.
Right now:
Huberdeau has 41 * 2 + 9 * .5 + 16 * .25 = 90.5 points
Tkachuk has 27 * 2 + -4 * .5 + 30 * .25 = 59.5 points
Karlsson has 28 * 2 + 4 * .5 + 14 * .25 = 61.5 points
Giroux has 22 * 2 + 5 * .5 + 18 * .25 = 51 points
My gut feel is that Huberdeau is a little ahead of where he should be, Giroux and Tkachuk are a little behind where they should be and Karlsson is about right. The point difference is about 21 points so for the remainder of the season, I would expect Huberdeau + Giroux to outpoint Tkachuk and Karlsson by 30 or so points.
This means that if Vas gets no shutouts for the rest of the season, then both sides would be within +- 5 points on this deal. If he gets 1, then you will break even or win on this deal. Any more than that, and you will win.
So it comes down to this. If there are certain players in the deal that you would prefer to own, then take that side. If you think Vas will get more than one shutout, then take his side. Otherwise hold steady.