This question has been thrown around since steroids and performance enhancing drugs (PED's) became an issue in baseball. If steroids did not enhance performance, then health risks would be the only reason to ban them. The first step to answering this question is examining the different types of evidence available today.
One heavily debated issue is the lack of, or inability to collect, direct evidence. People taking this stance believe that we can't connect the use of steroids to hitting a baseball more consistently or striking out more batters. To a point, this is true. No, we can't measure if steroids make you hit that spot on the ball, that propels it out of the park, more often. I cannot tell you if throwing a 96 mph fastball will always get more people out. However, taking a look at statistics of players using any type of PED's is a fair way to measure improvement or loss.
Statistical analysis is a very useful tool when trying to prove whether or not steroids make you a better baseball player. It allows to see the progression of a career with or without steroids. For pitchers, throwing a fastball in the high 90's will increase the amount of strikeouts during a given season. In order for some people to acquire this talent, practice is not enough. Players plateau, their speed becomes hittable, and they lose their effectiveness. Performance enhancers are the quickest way to add speed to that fastball and get on the fast track to the majors.
It is the same story for hitters. More strength means the ball will travel further when hit. A ball that travels farther will earn extra bases and home runs. Use of performance enhancing drugs has a positive correlation with the amount of home runs a player can hit in a season. Whether you throw the ball or hit the ball, taking steroids or PED's can help you increase the statistics that make players great. If that constitutes being a better baseball player, then these drugs do have an effect on players that launches them to the next level.