Many bettors like to play MLB parlays. The most popular parlays are those that combine big Money Line favorites. The idea is that the bettor can bet on -220 type bets without having to lay the -220. The truth is that the bettor is still laying the -220 on each leg of the parlay, and further he often cannot shop for the best line on each game since he has to bet the parlay at one specific shop.
A better parlay can be an MLB favorite to an OVER. There IS some correlation here, however one has to be careful. If a home team is favored, and wins, there is likely only 8.5 innings played, shortening the game. Therefore, home favorites parlayed to 'overs' typically do not make for ideal parlays.
The road favorite parlayed to the OVER however is a better correlated parlay. Here, you WILL get the full 9 innings of baseball, giving you the best chance to get OVER the total. Further, you can sometimes steal a road team and over parlay in extra innings where the game goes 3-3 after 9, but ends with the road team winning 7-3, etc.
Similarly, the home dog parlayed to the UNDER is a good correlated parlay as well. Here, you often will only get 8.5 innings played, and further if it DOES go extra innings and the home team wins, it will often be by just 1 run in the extra innings.
The run line parlays of these plays were, in fact, so strong, that books stopped allowing them. (One cannot play a -1.5 team parlayed to OVER 9.5, etc). The money line to total parlay is not as strong, but it can often be a great bet. The best time to do these is when you already like the road favorite AND the over, given this fire in a parlay also. Similarly, if you like the home dog AND you like the under also, consider making a parlay bet as well.
Let me emphasize, you will not make money blindly playing these parlays. You have to already like the games in question, but if you do, it can be a very powerful way to wager the games you like, when they are in the subsets discussed above!
In MLB today, I am going for my 11th straight 3* winner! I rarely play big favorites in MLB, but I am FIRING on one today, in a game I fully expect to be a blowout win. It IS a home team, so there is no correlation in play here, just one fine bet on a big home favorite!