A trend of N.F.L. underdogs covering the spread kept pace in Week 4, going 8-7-1 and bringing the season record to 36-25-3. The betting public must be on a lot of those underdogs, because this was the first losing Sunday of the season for a number of sports books across the country.
Don’t get too excited. The house might have lost in some spots last week, but don’t expect any Las Vegas bookmakers to be updating their resumes. Picking N.F.L. sides is a break-even proposition even as a theoretical exercise, and in reality gamblers need to be right more often than not because of the charges sports books pass on to the public through their lines.