They've proven to be very good at projections, whether that is their intention or not. There's a ton of research on that with ncaa basketball in particular, but for sake of argument here's one on MLB win totals. Since its a 7 year old article, it would figure that vegas has only gotten better at it since betting has exploded and Vegas predictions gets it strength from the crowd sourcing factor.
https://fivethirtyeight.com/features/the-imperfect-pursuit-of-a-perfect-baseball-forecast/