They weren't when DD was there.
MT actually took enough care to line match them away as hard as it is to believe.
When EGG was matched up against opposition top D and top 6 MT didn't do anything and let them play them. Probably partly because the 3rd line needed the soft matchups and that EGG managed to hold their own defensively while creating some offense chances (at least statistically more chances than their opposition while on the ice). During this stretch Galchenyuk constantly faced tough matchups but as a winger. I figured it was a way to speed up his move to center but not this soon.
If by chance MT actually puts Eller on the 3rd line with Bourque/Leblanc instead of the 4th with DD and other scrubs, theoretically PGG can have that DD type exploitation minutes as on paper at least Bourque-Eller-Leblanc should be able to go up against 2nd wave offensive players defensively.
Pacioretty - Galchenyuk - Gallagher
Bournival - Plekanec - Gointa
Bourque - Eller - Leblanc
Eller basically running as a Plekanec 2.0 with one of his regular linemates in Bourque + a young player who is sound defensively. A possible glimpse into the future where the Habs can stream 3 lines against anyone. Plek is still only 31 so realistically this can be the 123 punch at C for the next 4-5 years.
On the flip side...Habs called up St.Pierre, have Desharnais that they'll likely give 14min at least too/game, and White/Parros. I fear what MT will make as a bottom 6 and have a strong feeling it's going to be DD either on Eller's LW or St.Pierre. I doubt he's dumb enough to move Eller to LW.