How, if at all, would the game of hockey be changed if it went to a four 15 minute quarter format vs. the current three 20 minute period format?
The game itself wouldn’t change much. I suspect the biggest difference would be in “on the fly” line changes. The teams like to have their benches closer to their defensive end and rinks are set up so that is true for both teams in periods 1 and 3 but not 2. Assuming you alternated directions each period, you’d have it the “wrong” way half teh time instead of just one third of the time.
It might affect fans some who like to sit behind their goal or vice versa as well.
You’d have slightly better ice with the zamboni running every 15 minutes instead of 20.
Coaches would be able to shorten their benches with shorter periods, so there would be less ice time for fourth-liners and third-pairing defensemen.
I don’t know if that’s true or not. In basketball and football there is no time break except at half time. So you’d be playing 30 minutes straight of hockey with just the time for the Zamboni with a longer rest at half time only.
Something close to this has already happened in three instances of the Winter Classic. I haven’t seen most of them, but I don’t think the change had a huge impact on gameplay, other than evening up the environmental factors.
An even number of periods would certainly clear up any whining about asymmetries on the ice or arena, as in the above example of the Winter Classic. But another problem would be how long the breaks should be, especially from the standpoint of broadcast television and ice maintenance.
If they were the same length as they are now, it would add 18 minutes to the game’s wall clock time, which might upset stadium attendees and throw TV schedules out of whack.
If the breaks were shortened so the total break time remained the same, they might be too short for proper ice maintenance and for the players to rest and strategize.
Case in point: in 2013 the breaks were actually lengthened from 17 minutes to 18. At the same time, on-ice activities were cut back from 5 minutes to 4. That increased from 12 minutes to 14 the amount of time available for the Zamboni run and for the ice finish to harden, which the players considered important enough to make it an issue in the CBA.
I know the OP question is about the game itself, but this is another aspect of why the three periods in hockey are so intrinsic to the game.
How would football or basketball change if they switched to three 20 minute periods?
Games would be slightly longer and would feel slower, which would not be a good thing.
Basketball players would be very tired, comparatively.
Right. The need for ice maintenance is what sets hockey apart from other sports mentioned above. Running the Zamboni only at halftime would mean the ice is trashed for the 2nd and 4th quarters, and the players would never accept that. Running it after every quarter would drag out the game. Hockey is fun to watch because of its fast pace (among other things), and switching to four quarters would severely hurt that.
My impression is that a power play within two minutes of the end of the (non-final) period is a little less valuable, since at some point in the middle of the power play, the between-periods break comes, letting the defense regroup and rest, and then after the break the puck is brought back out to center ice and the offense has to get it back in the zone and set up, using up some of the power play time.
So, with four periods, penalties would be a tiny bit less damaging. Though I doubt enough to really change strategy much.
Not sure I follow that. If there were four periods, the breaks would change from 2 to 3. If you assume penalties are evenly distributed (probably not but nothing better is at hand for me), you have increased the chance of a penalty spanning a break would increase.
Right. And I think the break helps the defense more than the offense, so power plays would be on average less valuable. I wasn’t completely clear, but I meant that getting fouled (i.e. being awarded a power play) would be less valuable and committing a foul (having to defend a power play) wouldn’t cost as much. Again, by a really small amount, though.