Before the Houston Astros were wasting money on Brandon Lyon, they were a forward thinking team. General manager Gerry Hunsicker and head coach Larry Dierker employed a platoon of Sean Berry and Bill Spiers during the 1998 season.
The right-handed Sean Berry started 76 games and posted a .320/.390/.511 line in those games. Against right-handed pitchers in 222 plate appearances, he had a nice .276/.365/.458 line, but in 120 plate appearances against left-handed pitchers, he posted an outstanding .383/.429/.598 line. The left-handed Bill Spiers started 89 games and posted a .291/.373/.422 line in those games. Against right-handed pitchers in 396 plate appearances, he had a solid .287/.370/.415 line. In contrast, he had 41 plate appearances (which was 41 plate appearances too many) against left-handed pitchers and put up a measly .143/.220/.200 line.
Combined as third basemen, they put up a .303/.380/.461 in 708 plate appearances line with 43 doubles, 5 triples and 15 home runs. They were also both 32 years old. For comparison Cal Ripken Jr. posted a .257/.329/.420 line in 718 plate appearances with 26 doubles, 3 triples and 24 home runs during his age 32 season.
What does this all mean? Sean Berry and Bill Spiers are not name-recognition baseball players. By themselves, they were okay hitters but nothing too spectacular. Spiers was atrocious against left handers while Berry was decent against right handers. Combined they put up all-star caliber numbers. The teams that can't field a great player without a platoon split at every position have to be creative with their rosters to get great season-long production.
For those keeping tabs, last year general manager Ed Wade employed Geoff Blum and Jeff Keppinger as their primary third basemen. The switch-hitting Blum posted a .252/.316/.368 line in 386 plate appearances over 100 games as a third baseman. The right-handed Keppinger posted a .243/.319/.374 line in 244 plate appearances over 65 games as a third baseman.
Combined as third basemen, they put up a .249/.317/.370 line in 630 plate appearances with 21 doubles, one triple and 15 home runs.