Does base protect runner??
 

Had a discussion with a fellow umpire over the following situation: Less then two out and runner on base (no infield fly situation) when batter hits a pop fly close to a base that a runner is simply standing on. As the fielder is playing the fly ball, he runs into the runner who is standing on the base and as a result of the collision the ball is not caught.

I want to call interference on the play because I don't believe the base provides protection to the runner. Am I correct??

Assuming OBR, it depends. Standing on the base does not protect the runner from intentionally interfering. If you judge that he deliberately hindered the fielder by not moving at all, you can call INT.

I've never called this, so I'm not sure what exactly I'd have to see to judge INT.

The runner's action would have to be intentional. It's in the rule book:

Rule 7.08(b) Comment: If, however, the runner has contact with a legally occupied base when he hinders the fielder, he shall not be called out unless, in the umpire’s judgment, such hindrance, whether it occurs on fair or foul territory, is intentional. If the umpire declares the hindrance intentional, the following penalty shall apply: With less than two out, the umpire shall declare both the runner and batter out. With two out, the umpire shall declare the batter out.

The base doesn't provide protection from interfereing with the ball.

It does provide some protection from interfering with the fielder

Thanks to everyone for the clarification. :)