Just expressing an opinion really
I have watched England many times, both live and on TV, many times while Farrell has been captain. I do think (remember, it's only an opinion) that Eddie picked him as captain because he drives standards within the squad, particularly in training, and let's face it, Eddie has watched him closely since 2016, and he knows what he's getting. I don't expect to see a player's revolt like we did in France at RWC 2007, or players on the lash, like we did in NZ at RWC 2011 because he's setting a professional standard for other squad members to follow like a captain should. I'm not saying that he's the only one who could do it, but Eddie obviously likes what he sees.
If you ask me if I thought that Farrell is the best choice as on field captain, I'd say no, but I would say that he has matured a lot since he first took the armband. Do I think he deserves his place in the team based on form since RWC 2019? Probably not. But the media will go barmy in the lead up to the Scotland game and Farrell will be deflecting much of the white noise from Smith, which is exactly what Eddie wants.