The Portugal superstar was the clubs top scorer this season with 24 goals but has been criticised by some for causing a lack of cohesion among the squad. He became footballs all-time scorer with his hat-trick against Tottenham in March after breaking the mens international goals record in November.
But at 37, some believe his days are numbered. In fact, Carragher believes United cannot have someone at such an established age leading the line next season.
While speaking on the latest episode of the Overlap, the former Liverpool defender explained how Ten Hag must walk in the footsteps of Jurgen Klopp and Pep Guardiola by making a big decision when he arrives at Old Trafford.
He pointed to Guardiolas chopping of England number one Joe Hart at Manchester City and Klopps offloading of big-money Christian Benteke at Liverpool upon their entrances. Carragher then said: Im telling you now, Im convinced hes got to do that with Ronaldo.
Whether hes allowed to or not, and Ive said this consistently through this season, that was not a good signing. Cristiano Ronaldo is one of the greatest players of all time.
Man United cannot go into next season with a centre forward who will be 38. Even if he does score goals. Thats not right for Man United.
What Ronaldo has been doing at 37, scoring nearly 20 goals in the Premier League for Man United, is unbelievable. But he added: United need to buy a striker because theres only Ronaldo up there. Who do you buy? Someone to play or go on the bench?
Ronaldo will be a massive problem for Man United next season if he isnt playing every week. Weve seen it this season, even when hes coming off, he still kicked up a fuss.