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.
Sunday 1PM Slate
Marcus Mariota o179.5 passing yards -115 (DraftKings): The Falcons are 4.5 point dogs to the Chargers. The game total is 49.5. This number is simply too low given the projected game environment, and every projection I see backs that.
Drake London o38.5 receiving yards -120 (BetMGM): London is projected closer to 50 yards. Same game flow logic as the Mariota blurb.
Mac Jones o210.5 passing yards -125 (PointBet): Against a Colts secondary that ranks 20th in pass defense DVOA, Jones is projected consistently higher than this.
Khalil Herbert u45.5 rushing yards -120 (PointBet): Herbert receives a roughly 50/50 split with fellow running back David Montgomery. Justin Fields is also involved in the run game. Given the game environment (the Bears are 4.5 point dogs to the Dolphins who are 9th in run defense DVOA), it's hard to see the run game going off. Herbert is consistently projected lower than this number.
Tyreek Hill o7.5 receptions +114 (DraftKings): This number is about right, so I'd take dog odds on either side. Hill is up against a bottom tier Bears defense, not that anyone can cover him anyway.
Gabe Davis u3.5 receptions +120 (BetMGM): Davis is projected right at 3.5, so I'll take the dog odds here. The matchup against the Jets is difficult as well.
Joe Mixon u67.5 rushing yards +100 (DraftKings): Mixon is up against the Panthers, who are significantly better against the run (7th in DVOA) than the pass (27th). Carolina's defensive tackles have a big advantage over the Bengals interior line, as noted in the preview blog for this game. Mixon's game environment is fantastic (the Bengals are 7.5 point favorites), but I'm agreeing with most projections that have Mixon right at or lower than this number. Given the even money odds, I'm taking the under.
Amon-Ra St. Brown u74.5 receiving yards -110 (BetMGM): St. Brown has a tough matchup against a Packers defense that ranks 9th in pass defense DVOA. He's projected lower than this number.
Sunday 4PM Slate
Kyler Murray u265.5 passing yards -120 (PointBet): Murray's mean projection is consistently lower than this number. Yes, it's a great game environment for Murray (playing the Seahawks as 4.5 point dogs with a total of 49), but that could also explain why it's been bet too high.
Mike Evans o5.5 receptions +135 (DraftKings): I can't turn down the dog odds here against the Rams. Although it's true that Jalen Ramsey is an outstanding corner, he won't be on Evans all day. The corners behind Ramsey are struggling, which will give Evans a big advantage.