Geez,
There sure is a lot of b*tching & arguing going on. Does anyone that has contributed to this thread, actually shoot sports (HS/ U-18), and not from a casual standpoint??? It's a serious question.
Here's my 2¢.....
The OP does have a finite budget, but that doesn't mean one camera is better than another, because it has more Megapixels, a larger LCD, or a faster Frames Per Second capture capability. Pixels & FPS are marketing gimmicks. Give me a 300D/ Digital Rebel, and I will shoot the same shot, that you are recommending with the T2i/T1i. Lenses, ISO, & object of shot all being equal. Camera bodies do have limitations, as do lenses, but those limitations are there for a reason.
Here's what I'll recommend; Body wise I will recommend two. First is 8 year old technology, in the form of a used 1D. The 1D can be found for under $400 (Link-
http://www.fredmiranda.com/forum/search.php). Second is a 40D, which is only 3 years old, and can be found for around $500 +/- some $$$. (Link-
http://www.fredmiranda.com/forum/search.php)
Next since the OP's father is shooting daylight, I will suggest two lenses; Telephoto: 70-300 USM IS ($350 Avg)(Link-
http://www.fredmiranda.com/forum/search.php), Wide Angle: Tamron 17-50/2.8 ($350 Avg)(Link-
http://www.fredmiranda.com/forum/search.php).
Now onto my reasoning behind why I am recommending the 1D. Yes, while the 1D is "OLD" technologically speaking, when it comes to AF & locking onto a target, it will do better than any Rebel or XXD Body. Now the 1D ergonomically speaking, may be too big for what the OP's father is doing, but $$ for $$ it is the BEST bang for the buck. And while the 1D is lowly with only 4 MP, you can easily print 16X24's with the files that come out of it. It also has a shutter that tops out at 1/16000th of a sec for those bright & sunny days
The 3 (maybe 4) Biggest downsides to the 1D is, (1) that they chew through batteries, like we drink water (150-300 Images) per battery charge, (2) the Weight factor, & (3) the ISO gets really bad above 1250. Though I do know my share of 50 & 60+ y/o Photog's that shoot with 1D Bodies & 2.8 Glass. So the weight is more of a personal choice. (Maybe #4) is the small LCD (which is color). I don't use the LCD but to either change a setting in the menu, or to check my histogram.
Now, here is my other suggestion, which is the 40D. They sell anywhere between $475 & $600. The 40D does have a smaller form factor, has auto modes for those that never want to use a camera, the way it was intended to be used, and has lots of newer bells & whistles (Larger LCD, Better ISO, Smaller Form Factor/ Weight). Also shoots up to 6 FPS, has good tracking capabilities, and is easy to use & carry.
The lenses, I suggested are both excellent lenses, and will provide both a Wide Angle & Telephoto Aspect, with almost no loss of coverage. 20mm, is nothing to complain about. IS isn't useful for Sports, but it is useful for Statics & Low Light. Also the 7-3 is a great general purpose lens & a perfect telephoto lens for travel.
OP, I hope I gave you some food for thought, aside from the Rebel & 20D recommendations.