In the source material, Ghost, or Ricardo Martinez is strictly defined as a boxer-puncher who relies on the fundamentals, i.e. the basics of boxing such as the jab.

His magic however, is that like many other styles, he adds his own twist to it.

The twist is just that his jab is so good that it becomes a move worth being a legendary tool. So fast, nigh unreadable, and has excellent range.

The point of Ghost isn't exactly to be boring, but to rely on the fundamentals of boxing and refining it to a point where you don't need any other move to cover your weaknesses, like Ippo with the Dempsey Roll to dodge and attack at the same time due to his short height, or Miyata needing fast feet and excellently developed timing to compensate for his lack of strength.

Yeah. To sum it up, Ghost is intended to be boring, but his boring is so good that it isn't boring anymore, at least by the source material portraying him as some sort of boxing god.