New to covers. Been following for awhile. Since baseball is my fav sport to bet in decided to join to chime in. I think I know what you are trying to say dmc. If you look at best teams in baseball, say angels last year who won about 95 of their 163 games, that is still only a roughly 58 % rate of winning. So considering this, taking the huge line on favs every game is not a good strategy to win money in long run. It could also lead you to believe even the best teams win 58 percent on any given game. This is true of course, but keep in mind this is a long term stat measured over course of a season.
Were "capping" or whatever you want to call it comes in is deciding based on game game odds and many factors that change each game, which side is favorable. You are failing to consider pitching matching ups vs specific teams, different batting lineups, hot and cold streaks, batters vs pitchers, travel, night game followed by day game, teams who have worn out bullpen in previous games etc (i could go on for awhile). Considering all of these factors + the line i have no doubt in my mind you can pick over 50%. If you do not believe this you are not putting enough effort and research in to games that you are capping imo.
As far as capping bullpens. I disagree that is not possible. Take dodgers last year. Was comfortable betting them when I thought a pitcher could deliver a quality start due to their bullpen. Troncoso/belisario in 7th, sherril in 8th, broxton in 9th. That combo was very good all year. Various combinations of relievers can be recognized in every team. I agree while you cant predict every reliever that comes in in every game, you know which teams bullpen is reliable or not. I hope this helps.