When I played (quite a bit) in the 70's, the single goalie with raised
corner ramps were all that I had played on. I'm not sure when the 3 man
back rod became popular.
The three man goalie was introduced on the Tornado table in the early
80's to decrease production costs. The cost of the extra men was less
than the cost involved in crafting the sloped corners. Prior tables
had the traditional 11 players, and 1 man goalie rod.
I believe credit for this innovation goes to a gentleman by the name
of Ed Geer, who passed the idea to Ed McCloud at Tornado in 1981.
Obviously the success of Tornado in the high end coin-op foosball
table market now makes the 3 man goalie rod pretty much the standard
in the US.
Paul
Having played the game mostly in the 70's (competitively), I still have a
difficult time with the three man goalie rod. The one man goalie is second
nature, the three man I need to think about too much!