Many aircraft did poorly in ther intended roll only to become stars in
the roll they wound up in. An example is the F-111, it was to be the
air superority ground attack fighter for the Navy and the Air Force,
It wound up being one of the best ground attack aircraft in the USAF,
and never even made Navy service.

The F-105 was supposed to be the fast nuke bomber of the 60's but
became the workhorse of Viet Nam.

I am not at all sure the F-104 was a success, the USAF sure didn't
like it. NATO bought a bunch, but it's not clear that it would have
done well in Europe had it been necessary.

I guess its all in how you look at it.