Fact: players are too big for own good

The extraordinary transformation from the stamina-based rugby of the game's amateur era to the physically combative version served up by today's professionals is illustrated by The Independent on Sunday today in a unique comparison between this year's Lions tour and the trip to New Zealand in 1971.

The desperate plea for change made by Lions doctor James Robson at the end of the tour to South Africa in July, when the Scotsman warned that players were getting too big and muscular for their own good, is borne out by our exclusive statistical and subjective analysis. By comparing key indicators between the Second Test of the 1971 tour in Christchurch and the Second Test in Pretoria in 2009, the anecdotal theory that rugby has become a collision sport for muscular hulks is revealed as hard fact.

It follows a week of debate over injuries and the laws at the International Rugby Board's interim meeting in Dublin, and questions the whole approach to player safety in the contact areas of scrum, tackle and breakdown as well as the battles in the air.

We teamed up with rugby website ESPNScrum.com, TV channel ESPN Classic and statistics experts Opta Index to analyse complete footage of the 1971 and 2009 Tests side by side. Though the essential facets of the game are broadly similar, there were obvious developments in how the matches were played out, with much more reliance on power and contact. "Looking at the stats and watching the matches pointed to a hell of a lot more collisions in the game," said Graham Jenkins, editor of ESPNScrum.com. "What is quite clear is that players are taking the ball into contact rather than shifting it like they seemed to do in the 1970s."

There are fewer scrums now but the "hit" on engagement comes with markedly more impact. In 1971 the forwards mustered immediately over the mark and every scrum was completed first time. Today's packs are heavier by a combined 35 stones – on average, a 2009 Lions back weighed more than a forward in 1971 – and despite the "crouch, touch, pause, engage" protocol, scrums are often collapsing or being reset, with the attendant risk of wrenched shoulders and necks. The aerial game of 2009 – leaping high in the line-out, and jumping to catch restarts and garryowens – has no parallel in 1971, when feet rarely left the ground, and never by much.

Some other specifics are just as compelling. There were more than three times the number of tackles in 2009, and the tackles in 1971 were clearly of less impact. Only one, when the All Blacks' Bryan Williams ran into Gerald Davies near the end, was of the head-on variety which today routinely smashes the opponent backwards; the rest in 1971 were side-on or from behind so the tackled player was able to fall forwards in greater safety. In 2009, Brian O'Driscoll's tackle on Danie Rossouw without the arms wrapping round led to both players going off injured.

John Taylor, 1971 Lions flanker and ESPNScrum.com columnist, said: "Player by player now the guys make many more tackles. We didn't expect Barry John [at fly-half] to make any. There were fewer rucks in that particular match in 1971 than our other Tests, but when you did ruck you had to commit more forwards because you weren't allowed to handle the ball once it was on the floor." Nevertheless, the clattering "clear-out" collision by the Springboks' Bakkies Botha which dislocated Adam Jones's shoulder in Pretoria was nowhere to be seen in Taylor's day.

Davies, a wing in 1971 and the manager this year, called the 2009 match "brutal" and Taylor concurred. "With the size of the guys and how dynamic they are now, the intensity is shuddering. The sheer physicality of the Second Test this year was incredible."

As for entertainment value, that beauty remains in the eye of the beholder. The stop-start nature of the 92 scrums and line-outs in 1971 is countered by the match being done and dusted 20 minutes quicker than in 2009, with fewer stoppages for injuries and substitutes.