Who was the least dribbled past and what's the average for all defenders?
I don't know about averages, but looking at whoscored.com, sorting by dribbled past and scrolling down looking for full backs some of the results are:
-Flanagan - 1.7
-Ben Davies - 1.6
-Erik Pieters - 1.3
-Angel Rangel - 1.2
-Pablo Zabaleta - 1.1
-Kyle Walker - 1
-César Azpilicueta - 1
-Davide Santon 0.9
-Patrice Evra - 0.9
-Kyle Naughton - 0.9
-Gaël Clichy - 0.9
-Rafael - 0.8
-Danny Rose - 0.8
-Dean Moxey - 0.8
-Kieran Gibbs - 0.7
-John Arne Riise 0.7
-Luke Shaw - 0.6
-Leighton Baines - 0.6
-Seamus Coleman - 0.5
-Phil Bardsley - 0.5
-Billy Jones - 0.4
-George McCartney - 0.4
-Guy Demel - 0.2
That's per appearance, so I only included players with a lot more starts than sub appearances to avoid getting skewed numbers. Didn't include all full backs, but didn't purposefully leave anyone out. I avoided players that regularly play other positions too.
It's noteworthy that Ben Davies is so close to the top of that list, but at the same time it's worth noting that he's only 0.5 above a player like Zabaleta and 0.6 above Walker and Azpilicueta - 3 full backs that I think most here rate very highly defensively.
Obviously for any one player having a lower number would be better, if all other things are equal. But I don't think you can say that having a lower number makes you a better player. Unsurprising perhaps that Fat Sam managed full backs like Demel and McCartney are at the bottom of that list considering how well drilled they are defensively, how far back they usually sit and how much protection Allardyce asks his wide midfielders to give his full backs. The other regular Swansea full back Angel Rangel is also relatively high up that list at 1.2. I will repeat until the cows come home that this is about context and not looking at stats in isolation.
Going with the assumption that the context of the team surrounding the player is important I checked out Davies' stats from last season, where he scored 0.9 (per game, 33 starts, 4 sub appearances). No doubt that was a season when Swansea functioned better as a team, not a season where they struggled and sacked their manager. Now, it might be that Ben Davies was exposed more in his second season or it might be that he was found out to some extent by opposing wingers or there might be some other explanation for this, I honestly wouldn't know. But I think this illustrates the problem of just looking at a stat like this in isolation comparing two different players at different teams and trying to draw conclusions about ability.
Looking at our two full backs they're very close in numbers, but I rate Walker a lot higher (one on one?) defensively than Rose, yet Rose has a lower number. I think this can be at least partly explained by the playing style of each of them. Walker rather often gets very close to his winger, almost dares him to take him on and very often comes out ahead (imo). Comparably Rose stands off his man more, will fall back and perhaps not get dribbled, but also won't win the ball. So in addition to style of play of each team influencing these stats I think style of play of the individual full back makes a big difference. At least for some a style of play that means getting dribbled past a bit more frequently might be the better option overall. Who does Ben Davies play more like, I'm not sure myself?
I don't think stats like these in isolation is anywhere near a good indication of the actual quality of the player. I have to say that whenever I've seen Ben Davies he's seemed solid enough and hasn't seemed like the kind of liability a 1.6 number here might at first seem to indicate. But I did also watch him more last season and less this season when most reports have indicated that he hasn't been as good.