I presume Farrell is on the bench as he covers 10 and 12 (and I think Ford only plays 10?) - however Farrell could start at 10 and then move to the centres when Ford comes on, or something
Ford is by no means a bad player, but you would've thought that they'd go for Farrell who has more big game experience
As pointed out, Ford's the guy who's been with the squad and knows the systems.
Also, some rotation is sensible.
But finally... I know Farrell's been playing for Sarries, and playing well, but Ford has a reputation as being very very very special. I wouldn't bet on Farrell taking that 10 shirt off of Ford. Ford was ahead of Farrell last year. He played 6N games where Farrell was available at 10. If Ford keeps performing, I think he's going to keep the shirt.