I think Lazetic looks like a player, but await his fitness catching up (which could be a massive thing that takes until January, akin to Nisbet last season). We don't really seem to look at goals as a priority in our number nines under Thelin, more an all round link player that gets the team goals rather than themselves.
I don't think Yengi will go out on loan either, but we can look at the evidence from both Ambrose and Gueye that shows we will have a player rotting for a season without improvement unless they get game time. Of course, the idea would be that we get a player in at the same time as Yengi goes out, but I'd argue that would only be because Lazetic is injured and unproven rather than a numbers thing. I don't see a world in which Yengi gets a game if we get another striker in. He'd be down to fourth choice. For a guy who's biggest issue is confidence (I'm being generous, he could just be horse), letting him sit on the sidelines is extremely poor management. Although it could significantly improve the confidence of Sokler to know that the guy behind him is significantly worse. Not a position he's been in.