With Lallana out injured and Mayuka in Africa, we've been playing Guly Do Prado and Steve De Ridder. Would you not like some more competition for the 3 attacking midfielders in the 4-2-3-1 system?
In any case, why do you think signing Coutinho means they won't strengthen elsewhere? They can do more than one deal at once, plus we have signed an international centre back already this window.