To box in JKD as any style is a rejection of its primary principle: "No way as way; no limitations for limitation"
Even a non-martial artist can practice JKD. Michael Jordan is a JKD practitioner, though he probably has no idea what the term means. JKD is about self-actualization, the ultimate expression of the self through physical, mental, and cultural means.
A person who is only a good father can be a JKD practitioner. If he raises a child to be a valued member of society he has used his own self-expression to benefit the world and himself.
Don't get it confused with kicking and punching. Certainly the principles Bruce Lee articulated were martial principles. But these were merely physical manifestations of ultimate self-expression. There are vehicles (principles) that use other vectors as an objective, such as: sports, medicine, polotics, rhetoric, literature, music, and even love.
The Kama Sutra is a JKD document. Following its teachings allows for an ultimate expression of phsyical love.
JKD is about ultimate, efficient, self-expression.
What is ultimate for one generation (strategies and techniques) is not necessarily so for another. Therefore asking about JKD's performance in a venue such as UFC is baseless, really. JKD is not found in the performer, rather in the performance. All martial principles that seek to increase efficiency and lead to expression of the self are JKD. This includes BJJ's teaching on leveraging strong body placement against weak body placements. BJJ
is JKD.
So there