Jaskin's been strong in the offensive zone, namely along the boards and on the cycle. Unlike Yakupov, he knows how to position himself to aid his linemates. He hasn't scored, but he's been noticeable in a good way. I've been harsh on Jaskin in the past but his play as of late doesn't warrant him to be benched in favor of Yakupov.
Let's put it this way, I'd rather have a slower Jaskin who knows where to be on the ice over a fast Yakupov who is mispositioned basically every moment he's on the ice. You mention that putting Yakupov with Steen/Berglund will mask his defensive liabilities. I don't personally see it that way. I think it'll only amplify the issue since Steen/Berglund will be forced to cover for Yakupov and thus end up putting them out of position.
Jaskin takes a lot of flak, some deservedly so, for his lack of points and occasional glaring defensive miscues in the past. However, on the whole, he is a very good possession player. This is very valuable skill, even when it doesn't lead to points. He is strong on the boards, so he can keep the puck in the offensive zone longer than it otherwise would be. He is decent on the forecehck creating turnovers, or at least confusion. He is decent defensively when his foot speed doesn't hurt him. This usually means the other team isn't scoring (and is probably tiring themselves out fighting him).
There is a reason he is tied for first on the team in +/- and 4th in CF% (5v5). Plus/minus isn't a great statistic, but it can be useful in comparing players across the same team. There are only 4 Blues that are pluses. Jaskin is tied with Schwartz at a +5. This is because he helps generate chances (True, they don't often go in) but also minimizes the other teams chances. Add to the fact that he is starting to use his size to hit, and cause traffic up front, and he becomes more valuable. Even if he's not scoring, he can be a distraction standing in front of the net(e.g. game winning goal against the Wild)
Final point, its not just a cliché that power forwards take longer to develop than other positions. They have to grow into their bodies, get their strength up to NHL level, and learn to use it against much better competition. Jaskin has shown flashes of scoring ability. He just hasn't put it all together. Maybe he never will. But he plays a nice complementary game to either the 4th line or a #3 possession line with Berglund. There is no reason to abandon him when he is contributing just because he isn't scoring, especially when he still has some upside. When he comes off the ice, we are more often than not in a better or neutral position to where we were when he stepped on. That is all you can ask for from a guy making $1M. He's doing what Berglund does, only for much less.
