Most bettors still play the money line when they are betting on baseball. However, the run line is increasing in popularity every year. A quick crash course for those of you who aren't familiar with the run line - it's basically the same as the money line, except it incorporates a fixed spread. In a standard run line (there are variations, but I will only be dealing with this variety, the most common, here) the spread is 1.5 runs. That means that the favorite has to win by two or more runs in order for a bet on them t pay off. If they don't then a bet on the underdog is victorious. As a result, it is possible to find much more reasonable payoffs on the favorites because of the required margin. This can be attractive when dealing with heavy favorites. On the other hand, it is easy for underdogs to win in a run line, so the potential payoff is also much worse than in the money line.

As with anything, some teams are much better performers on the run line than others. Here's a look at four teams that are run line stars.

Atlanta - The Braves are a perfect example of why the run line can be worth a look for certain teams. If you had bet every game the team has played all season on the money line you would be a slight loser, though less than a unit. Not worth the effort. On the other hand, they are the best team in the league on the run line. There are a couple of good reasons for this. Most significantly, when they win they seem to win handily. They have respectable pitching and very good hitting, so they often win by a good margin. Incredibly, only one of their 28 wins on the season has been by just one run. The other side of the equation is that they are very good underdogs. They have been dogs of at least +110 nine times this season, and they have won six of those games. Even better, two of those three losses were just by one run. That means that they have paid off on the run line in eight of the nine games they have been underdogs.

Tampa Bay - I've said a million times that I am shocked by the magnitude of the success of the Rays so far this year, but I can never say it enough. They are playing fantastic baseball, and they currently have the best record in the sport. They also have been particularly kind to bettors - they are the second best team in the league both on the money line and the run line. Their formula isn't very complicated - they have assembled a great deal of young talent, and those players are pitching and hitting reasonably well. That's all it takes to win. When it comes to run line success, though, they haven't done it in quite the same way as Atlanta. Seven of their 32 wins have come by just one run and they are just 5-6 when they are underdogs of at least +110. They've done well on the run line for one main reason, though - they just keep winning. As significantly, it has taken the public a while to believe in this team, so they have been winning at prices that are often more inflated than they should be based purely on the team on the field.

Florida - Last year the Marlins were the third worst team in the league on the run line. In the offseason they traded away their two biggest names without getting equal marquee talent in return. Now they are the third best in the league on the run line. No one ever said that this game makes sense. They are also the best team in the league on the money line. Neither result is surprising. No one ever thought that this team was going to be even remotely competitive, so they were able to pick off a lot of wins as underdogs, or as lesser favorites than they would be if they were a team other than the Marlins. They have been an underdog of at least +110 a whopping 31 times so far this year. That's ridiculous for a team that is 30-21, but it speaks strongly to the public perception of them. They have won 16 of those games outright, and lost another three by just a run, so that alone accounts for the level of success enjoyed by Florida supporters.

Houston - There are some shared trends among the teams on this list. All of them have had very solid starts to their seasons. All of them are performing significantly better than most people probably expected them to be doing. They are all among the top dozen teams in the league for batting. Where they differ is pitching. Atlanta and Tampa Bay both have staffs ranked in the top eight, while Florida is in the lower half of the league. Houston is way down in the bottom third. Like Atlanta and Florida, the Astros' run line success is largely due to their strength as underdogs. They have been at least +110 28 times this year, and they have won an impressive 16 of those games. Five more of the losses were just by one run.