Rodman kind of overdid his workhorse and role player attitude, though. He was a two-time all-star and recognized as the defensive player of the year twice, then made the all-defensive team seven times, so he didn't, exactly slip through anyones radar come game time.
The tall guys of the NBA, like PJ and Mutombo, are in a different class. Mediocre centers tend to really be bums who end up staying in the League mainly because they are tall, or manage to be only defenders. These guys were primarily defenders, though Brown wasn't much of a shot blocker.
Harpring is pretty close to this kind of player, though he was a fairly high draft pick - 15th that year - so he was somewhat expected to be good, at least. No guarantees on that, but he was an All-American and then he made the All-rookie team his first year. He is also in that size class of 6'7" to 6'9" that I are talking about.