If the miner with the strongest ability to solve the block wins, why doesn't the same miner win every time? Wouldn't that miner still have the strongest ability to perform the proof of work on the next block and thus win every block?
Mining is not won by the miner with the "strongest ability to solve the block".
Mining is a random process, not a linear stack of work that needs to be powered through. This is because each miner works on different inputs to their block: As everyone is trying to send the block reward to themselves, they are using different Coinbase transactions. Therefore, the miner with the most hashing power has the greatest chance to win the block, but it is by no means guaranteed.
Think of it as people buying lottery tickets corresponding to the speed of their miners: There are only so many winning tickets in the pot, but somebody might get it on their fourth try, while another has bought fifty losing tickets already.
For a better overview what mining is, you can have a look at "What exactly is mining?".