Why don't we compare their stats from this season, when Fabregas actually plays as a midfielder all the time and is trusted by his coach?
STAT                
Tackles won          Fabregas  - 
36.          Rakitic - 12.      Fabregas can't defend, yep. 

Aerial duels won    Fabregas    12            Rakitic  12
Interceptions         Fabregas    11            Rakitic   
17
Clearances            Fabregas    
17      Rakitic 6
Blocks                  Fabregas     2             Rakitic   2
Total passes         Fabregas  
1323        Rakitic  941
Chanced created    Fabregas   
53            Rakitic 17  
Assists                 Fabregas   
12             Rakitic 2
Goals                   Fabregas    2             Rakitic  
3
Shot accuracy        Fabregas    
67%        Rakitic   43%.
 
If he were used correctly and was trusted to be the main CM, he could have done the job for us. His talent hasn't gone anywhere, and that talent is clearly much superior to Rakitic's. It's annoying that even Mour knows how to use him, but we couldn't. I've seen several interviews of Fabregas after he went to Chelsea and every time he said that he feels happy at Chelsea, he feels important. The lack of trust can make a world-class player seem average.