For the most part, their predictions are very similar. I take a look at the six biggest European leagues every weekend and there's rarely more than 3pc difference between the Betfair price and 538.
Long-term forecasts on 538 don't tend to change as rapidly as the odds can, which I tend to...
Not so, on 538 at least. From their "How This Works" explanation:
"Shot-based expected goals are an estimate of how many goals a team “should” have scored, given the shots they took in that match. Each shot is assigned a probability of scoring based on its distance and angle from the goal, as...