This is a common misconception. Vanderbilt is usually weak in football but not usually the bottom of the barrel. In the last three years Vandy has averaged just under 5 wins per season, and been on the verge of a bowl berth twice.
But in all other sports, Vanderbilt is very competitive, and sometimes actually carries the SEC banner. Vanderbilt has gone to the Sweet 16 in 2 of the last 4 NCAA tournaments and is currently in the top 20 looking to repeat. Vandy goes to the NCAA tournament regularly and Memorial Gym is known as one of the toughest places to play in the NCAA. Vanderbilt women's hoops are blue chip- in the same breath with UT, Duke (this used to include La Tech but not so much anymore). The Vandy women's team is always top 10.
Vandy was #1 in baseball most of last year, and has been the top rated SEC baseball team for a while now. It has a reasonably solid history of baseball, especially in recent history. Currently #3 AP.
Vanderbilt golf teams are always strong and ranked, often in the top 5. Men and women golfers at Vandy go on to pro careers. The school also has a strong tennis program.
And the school is far and away the top rated academically - and it is after all a [i[college[/i] conference, not an athletic farm association. ;)
For a school of 7,000, I think Vandy does quite well in the SEC.