If your video includes lots of motion, this eats up bits in MPEG. If you have a low bitrate set, MPEG may not have enough bits to clearly encode your motions, and the quality will degrade and noticeable artifacts will be introduced. For a sports video, which I would guess is highly active, high bitrate is probably a must.

I often use max=9.8Mbps and average=8Mbps. Other forum posters reject this, saying bitrates this high cause compatibility issues with some DVD players. Might be true. I haven't had any issues yet, and I want the best quality possible, so I do this. Another downside to high bit rates is that the DVD will fill up faster; don't expect more than an hour at these rates.

I would also suggest VBR(Variable Bit Rate) and 2-pass encoding(perhaps this is only v5?). VBR allows the encoder to steal bits from frames that don't need it to encode frames that need more bits. 2-pass encoding will actually render twice: the first time it just looks for good places to add bits and the second time it actually renders. 2 pass increases rendering times by a LOT, though, so be prepared to wait a bit. You might wait till you render your final copy to perform 2-pass.

People debate heavily on how much 2pass or VBR really helps, but I think what it really comes down to is that it depends on the source video. I think, however, that using VBR and 2-pass will never degrade your video; it just takes longer and perhaps is not GUARANTEED to improve the output.

-Jayson