The bets are determined by checking a wide variety of projections against my own knowledge of how players will be utilized given game context. The player prop lines were taken from this site.
When analyzing projections from fantasy sites, you'll often find that the projections are higher than betting lines, which will make you bet shit tons of overs. This is a common mistake. The projections are mean based, which tend to skew higher because the range of outcomes are not evenly distributed. (i.e., a running back on a good day could go for over 100 yards, but he would never go under 0... hopefully). If you find a mean projection lower than the Vegas line, the under is likely a good bet. To bet an over, the mean projection should be significantly higher. All bets below will follow that logic.
Sunday 1PM Slate
Kirk Cousins u258.3 passing yards -113 (FanDuel)
Dak Prescott u15.5 rushing yards -110 (Bet365)
Rhamondre Stevenson o37.5 rushing yards -114 (FanDuel)
Najee Harris o41.5 rushing yards -110 (Bet365)
Dalton Schultz u38.5 receiving yards -110 (Bet365)
DeVonta Smith o4.5 receptions +120 (DraftKings)
Matt Stafford u0.5 interceptions +140 (Bet365)
Sunday 4PM Slate
PJ Walker u200.5 passing yards -120 (PointBet)
Pierre Strong o22.5 rushing yards -110 (Caesars)
Brandon Ayiuk o65.5 receiving yards -115 (DraftKings)