For my case, I had a better DR (DR/MR, lower 6 stars, 19 y.o) in the starting line-up and a DR (91%, 33 y.o) on the bench. Two times in a period of a few days, I have been recommended a 30 y.o DR to replace the DR that was on the bench (as shown above). The 19 y.o DR in the line-up was far from the weakest (quality-wise) among the 11 players too. The only plausible reason for the game to suggest me a player to replace the DR on the bench is that the player was old but then it would have said like this player is getting old bla bla bla like Gert Funk showed in one of his post.
At that time, I also had a fast training 18 y.o DR/MR/AMR (at about 78% quality) that was bought as a player with the potential for act as cover or even to replace the first team DR in the future. So, my team was decently covered for this position.
I did get some good 18 y.o players (AMR/AMC/AML, DC, MC) as recommendations before though. Maybe because I did not buy, the game started to send me much older ones. Well... this is madness to buy such players in the last week; if those 18 y.o came in the first week, I may have bought one, but no way I would buy that 30 y.o DR.