The stack size is an important factor when having a strategy
Poker is very similar to Blackjack regarding the stack size which is not the case in Backgammon, since there are no cards. Anyway, In Blackjack the stack has a major impact on the game as in Poker or online Poker.
If you have a small stack the gap decreases, meaning you cannot afford to risk chips by stealing raising weak hands. And because of that, other online poker players will be less inclined to call or re-raise you unless they have a very strong hand. This due to the fact they know you cannot bluff with a small stack and they will not be as quick to gamble against you with weaker hands because there is a little for them to win. Therefore your chances of making a successful are actually bigger.
On the other hand an online poker player with a big stack might be willing to gamble with you because they will not be risking you. Yet, with a medium pack is a bit more difficult because you will have to make a number of difficult decisions since at the same time you are trying to avoid becoming a short stack.