It seems like college football and the NFL make big changes to their rules every year, and those rule changes often have a big impact on the outcome of games, so it is important for bettors to keep up to avoid making mistakes. Thankfully, baseball doesn't change its rules that often, and the changes are mostly cosmetic or minor instead of significant, so it isn't as important to keep up with the changes from year to year. That hasn't always been the case, though. There have been some MLB rule changes through the years that must have really messed with the sports bettors of the time. Here are five of the MLB rule changes that, I can only imagine, must have messed with the minds of bettors at the time:

1920 - The spit ball is outlawed. After decades of being able to doctor the ball with whatever you pleased, the umpires outlawed all illegal substances on the ball. Sort of. They instituted a grandfather clause for the season, so each team could designate two spit ball pitchers for the 1920 season. If such a rule were to happen now, as impossible as it seems, it would be a nightmare. For the first few weeks at least we'd have no idea which pitchers were successful because they were talented, and which ones were successful because they had sticky saliva. Batters would be just as confused, too, because they wouldn't know what to expect from any given pitcher. And on top of it all, if you believe that stories of the time then most of the batters were drunk most of the time, so that was an extra wrinkle.

1935 - The first night game is played. It happened on May 24 in Cincinnati, and I am sure that it seemed like the whole world had ended for baseball purists. Daylight was a given up to this point, and now all of a sudden people had to figure out how playing under the lights would affect everything. The lights almost certainly weren't as bright as they are now, so bettors would have to figure out how well the batters would see the ball. And the pitchers, too, for that matter. I'm sure that the public would have panicked like crazy if this were to happen now. Chaos.

1952 - Four umpires becomes the norm. Sports bettors can have a tendency to be paranoid, and they certainly don't trust officials of any kind, so this would be the definition of a nightmare for many of them. People would have been fearing that umpires would have just got in the way, and that more of them would mean more arguments and more wasted time.

1973 - The DH rule comes to the American League. I'm still not sure I am a big fan of this one. In fact, I'm pretty sure I'm not. I suppose the DH makes the game more interesting because it interjects a better bat into the lineup. The cost of that, though, is a loss of a great deal of strategy and intrigue. I've had a whole lifetime of watching the DH to form an opinion on it and to compare the subtleties between the presence and the absence of it, but at the time it would have been confusing, and it would have been very easy for bettors to overcompensate for the impact they expected it would have.

1978 - Change in how E.R.A. is calculated. This is by far the most subtle change on this list, but for the stats freaks it would have been a challenge. The way that the ERA was calculated changed to use fractions of innings. Previously, a pitcher got credit for a full inning even if he had only recorded one out. That would have the effect of increasing the average E.R.A. across the league, and making it more difficult to get a sense of what a particular E.R.A. actually meant until you became used to the changes. It would have been a particular challenge for bettors with a long-term view because it became harder to compare how a pitchers ERA had changed from the 1977 season to 1978.