He was the prototype of the WWF cruiserweight and flying wrestler in the '90s before the arrival of the new wave that didn't last long after him (such as Taka Michinoku and other cruiserweight wrestlers in the 2000s).
He started his first run with WWE in 1993 as the 1-2-3 Kid and he received a decent push in the mid-card that really started when he defeated Razor Ramon on the May 17 episode of Raw. He then defeated Ted DiBiase and his career was launched.
With his small size, he played the face underdog perfectly. The fans really liked the breath of fresh air he brought in WWF with his quickness, his high kicks and his aerial maneuvers.
In the next two years, a lot of things happened to him; he gave a hard time to Bret Hart in an intense WWF Championship match and he eventually became a quiet member of The Kliq. He also won the Tag Team Championship twice, once with Marty Jannetty and once with Bob Holly.
With his rising popularity, the fans were shocked when he suddenly turned heel and joined the Million Dollar Corporation in October 1995. However, his heel character didn't work very well, and he was not used a lot until he left for WCW in 1996.
In 1998, he came back with the WWF in what was considered the Comeback of the Year by Pro Wrestling Illustrated. X-Pac was born and he joined the DX Army along with Triple H, Chyna, Road Dogg and Billy Gunn.
The next year, after being fired from DX, he formed a solid face duo with Kane and they won the Tag Team Titles twice. In 2000, he betrayed Kane to join back DX but, since then, he received almost no push and he was put in secondary story lines.
He never reached the main event status and he eventually left in 2002. His only achievements in singles competition were to win the European Championship twice and the Cruiserweight/Light Heavyweight Title three times.
However, despite his limited success, he had a solid and permanent impact on WWE and he connected very well with the fans. He was spectacular in the ring with his high risk maneuvers and he popularized the Bronco Buster. He can even be considered as a "feet wrestling" pioneer.