Akainu was much stronger than WB, the two times they faced each other in the war he came out on top. If you only saw the anime you probably imagine that WB was dominant, but in the manga it was destroyed by Akainu. The admiral came out with just two cracked ribs and went on to fight all of WB's commanders calmly, while WB came out with half his head ripped off, his chest blown out and his organs burned, feeling pain just from moving. It was a complete one-sided massacre.
