Most of the rules of The Hundred don’t produce big differences to a T-20 game, but the differences to “an over” can have some effect.
In many ways, the special rules of The Hundred — most notably the 100-ball limit on innings — are simply proportional tweaks to the 120-ball T-20 format. Bowlers are allowed a maximum of 20 deliveries (the same 20 percent of the team total that applies in most limited over formats), while the Power Play lasts 25 balls. One theoretical difference is that teams might play more specialist bowlers and fewer specialist batters because there’s less time to lose wickets and get to the middle-order batters. In practice, teams often instead simply play more aggressively, knowing they still have competent batters to come in if somebody gets out.
The biggest change to the actual gameplay is that The Hundred doesn’t use the traditional format of a six-ball over delivered by one bowler, with a change of ends (and thus a different bowler) after each over. Instead the change of ends comes every 10 balls, while the bowling team has the option to change bowler every five balls.
Most of the time the bowling team changes the bowler after five balls. It appears teams are more likely to keep the same bowler for 10 consecutive balls if they appear to have momentum from taking a wicket or not conceding many runs. The downside is that delivering 10 straight balls can be mentally and physically tiring.
These rules may also change the batting teams tactics if they only have one wicket remaining and a strong batter is partnered with a weak batter. In this scenario the weak batter may try to play defensively to survive until the end of the over and let the strong batter regain the strike when the bowling end changes. In The Hundred, with fewer end changes, there’s a greater chance this would involve playing defensively for so many balls (potentially 10) that the wasted opportunities to score outweigh the risk of the poor batter getting out.
One minor rule change with The Hundred that can have an effect is the “strategic timeout” where the bowling team can call for a break of 90 seconds during the innings. This is mainly an opportunity to regroup and discuss tactics. However, some teams will take the strategic timeout when batters are on a consistent run of scoring well and looking comfortable, the idea being to disrupt their momentum and even break their concentration.