A variety of things could've happened: stored up actual chickens, having chickens prepared from uncommon/rare champs to snipe a win at the end, stored up books, having brews ready to take rank 5/6 champions up, etc. 

It's unfortunate but it's definitely quite easy to dump points in training tourneys. 

Champion Training is a tough one. There's a technique that you can use to get 1000s of points in less than 2 hours easily. Tossing Brews at Rares/Epics that are level 1 before feeding them to a full leveled Rank 3 or 4. I use 1 brew for a Rank 3 and 2-3 brews for a Rank 4. Here's a good example:

You have 4 Rares that are all level 1. You toss 1 brew to 3 of them and get 10 levels for all 3. Then you toss 10 brews at the 4th, which gets them to 30 and then you use the 3 level 10 rares to rank the rare to 4. THEN you toss 3 brews to the Rank 4 rare to make them level 18. That all takes less than a minute and is worth a decent amount of points. 

I got 1000s of points in one tournament just by tossing brews at all my Faction Guardians since they were all level 1 Rares and Epics

"There's a technique that you can use to get 1000s of points in less than 2 hours easily."

Okay, sure, but is it possible to dump over 9000 points in 45 minutes? That's what seemed so weird. I was well over 5000 points ahead at that 45 minute mark, and when I checked the rankings this afternoon, I find that participant #2 had increased by over 9000, supposedly before the tournament ended less than 45 minutes later. Is that really possible? Like I said, I'm new to RAID: Shadow Legends, but that really seems hinky.

Yeah, sniping in champion training is quite normal. Having a big store of books you can drop on champions is probably the quickest way to do it. 

100% within the norm. remarkbly easy if someone has stored and/or purchased books, chickens, etc.

as has been said, sniping is really prevalent in champ training and is very much a "it's not over until it's over" kind of tournament. 

Okay. I appreciate the info and y'all explaining things to me. Like I said, I normally don't compete, so I'll just stick with that from now on. 

Trying to take 1st place in any champ training tourney is often a losing prospect.  

Other tourneys are often very different.  No reason you won't be able to win some others.