Cause:
1. He was translating one piece raws over at APForums unofficially for like 6-7 years, like CNET, via scripts. Many people consider his scripts WAAAAAY better than the first ~60 volumes originally translated in One Piece
2. He was officially hired by ViZ by volume 65. He has to basically "conform" to ViZ translation policy and is stuck with Zolo, "King of the Pirates" and more playful dialogue/flavor text, but most people agree that his translations are super accurate.
3. He provides deep explanations as to why he translates things a certain way, when people ask. You can check examples in his Twitter threads.
4. Hes not a dick as a result of people questioning his work.
Edit:
https://web.archive.org/web/2010031...gascreener.com/stephen/onepiece/onepiece.html
If anyone is curious about his earlier translations of volumes. He's very passionate about what he does.