How to Tell Which Team is Ahead
There are a couple things you can look at. Between champions that are laning against each other, the one with a higher level or more minions killed is usually ahead. Total team gold and towers taken, both of which are displayed in the spectator overlay, are usually good indicators to tell which team is ahead. If one team is ahead by 5k gold at 20 minutes, that's a pretty big deal. If a team is ahead by 10k gold at 30 minutes, that's a pretty big deal. If the game is still going on at 50 minutes, it's harder to tell. Positioning on the map also plays a part. If the champions are all near the blue team's base, the red team is probably ahead. If the champions are all near the red team's base, the blue team is probably ahead.
One other really important thing to keep track of is the current state of Dragon buffs. The team that managed to acquire more Dragon buffs is usually in the lead, although this also depends on what kind of buff it is. Usually, the casters will go into this in more detail, often explaining which Dragon buffs enhance certain team compositions.
How to Watch a Teamfight
Teamfights can be very confusing to watch if you don't already have a very good understanding of how the game works. So if you're completely new to League of Legends, you should do just two things.
- Figure out who each team's Carry Champions are.
- Watch to see which team's carries die first.
Generally, the team whose carries die first will lose the teamfight due to a lack of consistent damage.