For the large majority of people, an original black hammer is going to be little more than a spare ball.
I love my old Hammers, and I will probably always try to keep some around, but I am VERY old school and sentimental. Some of my best performances ever were using them.
For the majority of modern players though, they just aren't strong enough, and don't give them the look they are familiar with.
On TRULY dry lanes, they will still start early, but the cover stock just wasn't built with today's oils in mind, and it doesn't handle them well.
They were always a very "rolly" type reaction for me, picking up a good roll without hooking too much. This was conducive to playing the track area back in the day.
To see what I mean, go to youtube and watch some videos of Del Ballard from the late 1980's/early 1990's. He threw lots of old Hammer stuff back then, and you can see the nature of the ball on the condition it was intended to be used on.
