They had a much better balance in terms of goals last year (and other metrics).
2017/18 - 5v5...
Scheifele / Wheeler / Ehlers: CF% 53.4, 7 GF, 6 GA, GF% 54
Scheifele / Wheeler without Ehlers: CF% 50.5, 37 GF, 25 GA, GF% 60
They simply haven't been as effective this season except with Ehlers. My "eye test" is that they have been spending way too many shifts hemmed in their own zone, unable to regain possession or get a clean zone exit, except when Ehlers is on LW. I'm not sure if it's because of their competition (I doubt that explains most of it), or just a general decline in defensive effectiveness (my hypothesis).
Regarding Ehlers and Laine, they have been effective together but not with Little at C. Both Stastny and Copp have had some positive results with them.