Okay Chief.
The main benefit of your steroids/HGH is recovery. By using them alone, you do not get stronger. You have to still hit the weights. When you lift to gain strength, you break your muscles down, and your body will heal/recover naturally. When using steroids/HGH, you body heals/recovers faster allowing you to workout harder and more often. As you probably know, a 162 game baseball season is a grind. How many times have we seen various records on pace to be broken at the All-Star break, but the player falls off in August and September. Some of that is due to nagging injuries and the grind of the season. So, if you are taking steroids/HGH, those nagging injuries heal and don't take away from the players production near the end of the season. If you have noticed, there have been just as many pitchers (recovery between starts) taking steroids/HGH as position players.
With that being said, HE CHEATED, and so did everyone else who took steroids/HGH. What the PEDs allowed McGwire to do, is stay on the field and not have to sit out with nagging injuries later in his career. As McGwire, Bonds, and....., got up in their careers, they became much more knowledgeable and smarter hitters. But, instead of age and injuries keeping them on the bench, steroids and HGH kept them in the game. Thus, more homeruns.
Randy