Would make your CM strength in depth the best in the league if you did get him, however the real issue is just a lack of a goalscoring/creative winger(basically what Depay is meant to be). Most of your problems is down to that and injuries.
Also I feel like Blanc has managed PSG quite well. Consistently in the Quarters of the CL, guaranteed league title for them. Furthermore he took France to the quarters of the euros and got them playing good football as well.