Here's a cool article I found in a Maple Leafs program from 1959. It talks about how they used to track each player's time on the ice back in the 1950's. It seems that Punch Imlach was somewhat interested in who was on the ice and in what situations. Sounds like the beginning of advanced statistical analysis if you ask me. All in italics below is the original article.
These clocks, installed in 1951 are a Gardens "first" in the NHL. Wilf Snowden and Billy Calvert trigger the timepieces with two panels of switches which they operate in the booth west of the band. From their vantage point they keep track of the players on the ice for both teams. The panels - one for the Leafs, one for the visitors - have 18 "on-off" switches each. Beneath each switch a player's name is inked on a strip of white adhesive tape before the game begins. The names are arranged so that the switches for players playing together are side by side. Wilf and Billy can then quickly flip the switches as the players change.
A few years ago I was able to sit in the press area at Rogers Arena for a Canucks game. I sat behind a row of guys worlking for the NHL doing pretty much the very same thing 50 years later. They were tracking ice time, hits, takeaway's, giveaways, blocks etc. Each entering in realtime onto NHL.com. They may as well have been flicking a switch on or off 50 years ago.
The 36 clocks - ordinary kitchen variety - are in a small room behind the west blues. Under each one is the name of the player who's switch in the booth is connected to his clock. the giant Sportimer over centre ice is also wired into the clocks. When the timekeeper at ice level starts and stops the Sportimer he automatically controls the clock for each man on the ice. After each period Don MacKenzie records each player's time in minutes and seconds. When the game is over the Leafs' times go to Punch Imlach. The visiting coach is given his players' totals.I guess the coaches had no interest in the stats for the opposing team, only their own, strange.
Sometimes Don will get a call for the times at the end of a period or even during a period if a coach wants to check on a particular player. If a man's not in good condition he can't very well hide it if he's tiring after having little playing time. It's harder to cover up injuries, too. Time on the penalty bench is not counted. When Gord Hannigan was with the Leafs he once got into a game to sit out a teammate's penalty. His total playing time was logged at 4 seconds - the time taken to get back across the ice to his bench after the penalty expired. "Too slow," said coach Hap Day, when he saw the times after the game. "It shouldn't have taken him that long." It turned out that in the excitement of the game the switch for Hannigan hadn't been thrown for his short skate. This was found out when the clocks were checked after the game so they time was estimated at 4 seconds. This was a bit too long and Hannigan got a ribbing from his teammates. They wanted to know if he'd crossed the ice by way of the goal. "Wind sprints for you tomorrow," they kidded him.
Hannigan, a Centre scored 17 goals for the Leafs in 1952/53 and 29 total in his 161 game career.
Because of his experience Wilf handles the switches for the visiting players. For two periods they are skating towards him. He has to recognize them by some means other than the numbers.
"There are different ways to do this," he explains. "Some you get to know by their style. Tom Johnson of the Canadiens seems to run on his skates. When Allan Stanley played for Boston I could pick him out by the deliberate way he moved out of his own zone. Jean Beliveau's size and Gordie Howe's relaxed style easily identify them. Gus Mortson has the habit of thumping his shoulder pads while skating to his position. Of course, the helmets help a lot. Charlie Burns is easy to spot."
Today's (1959) iron men log more than 30 minutes' ice time each game. In recent appearances at the Gardens Howe and Andy Bathgate were clocked with 35 minutes. Doug Harvey usually goes for 37 or 38 minutes. Allan Stanley and Tim Horton are on about 35 minutes.
37 minutes for Doug Harvey. 35 for forwards Howe and Bathgate. Amazing. Of course rosters were slightly smaller back then, but imagine getting to see Crosby, Ovechkin or Toews for over half of the game. It's incredible that with the comparative lack of conditioning the players had 50 and 60 years ago that they were even able to play 35 or more minutes.