He's been absolute garbage and the only reason he's even talked about as a possible sub is because of his crazy wage and transfer fee. He would never feature for us again for the remainder of the season if he had been a cheap transfer. Its quite shocking really how bad he has been coming with that price tag.
I know of you think this (absolute garbage) but he has been some better most of this spring than fall. Coutinho usually has many decent interchanges with Messi and Suarez when they play together in a match, and that have led to goals or clear chances. He still gives possession away more than he should, but it is less than the fall and with more positives. Now it is quite clear Dembele adds a whole another dimension vs Coutinho, and fans often focus on this particular contrast (as if Dembele isn't even more superior compared to Malcom, D. Suarez, Prince, Rafina, Munir or Alena when we have tried them up top this year). Until maybe 2 weeks ago everyone was saying Suarez is garbage too and we should drop him, if we reacted that whim who knows where we would be in all competitions but probably not as strong as place as we are. Comes with the territory of being an attacking player and when a lot of risks don't work out and you have a dry spell in goals. People (ill informed) are calling Salah garbage too--yeah he is on a goal drought but he is creating in lots of other ways and Liverpool would be fools to drop him just as we would have been fools to drop Suarez a month ago.
I know some of you are not fan of metrics but Coutinho is somewhere in the middle of the squad (e..g., whoscored, sofascore). He is nowhere near as good as Messi (another planet) or as good as Dembele, Suarez, Pique, Alba or Busi, but on a per minute basis he is ahead of the other attacking players who he might compete for PT with--e.g., Alena and Malcom, and splits even with Vidal.
Has he been worth his fee? Of course not. Based on his all around effectiveness should be the 1st guy off the bench if Messi, Dembele, & Suarez are available, or to start if one of them isn't, absolutely YES. At this point--middle of the season--I don't want players punished or rewarded because they are cheap or expensive. I just want them to be played based on their pitch contributions relative to alternatives in the squad. I would want any manager to look at it that way too.