Baron Gold

Baron itself is worth a substantial amount of gold to the team that kills it. Then, the baron-buffed team (usually) kills several turrets (worth a lot of gold), farms the enemy jungle (worth some gold), and if sufficiently coordinated, prevents the enemy team without the buff from doing anything meaningful (other team doesn't get much gold).

The broadcast team keeps track of how much gold the buffed team gets relative to the un-buffed team during the buff duration. Thus, the "baron power play" representing how much of an advantage one team accrued in 3.5 minutes over the other.