Never let it be said that rugby union is not pulling its weight in the economic crisis.

Its latest job-creation scheme has already been implemented with the increase of matchday squads to 23, with three specialist front-row players among the eight replacements.

Now the Image of the Game task force is proposing the introduction of rolling substitutions – a measure which will not only offer gainful employment to the official given the task of recording all the comings and goings, but could significantly extend the careers of key specialists such as scrummaging props and goal-kickers.

The task force is keen to stress that while rolling substitutions might as a side-effect prolong a few careers, the real motivation behind its recommendation is player welfare.

As the rules stand, the medics have only a minute to make a judgment call on head injuries. The pressure is on; the player himself is very often keen to continue, his team-mates are anxious to get the game re-started and coaches hate having changes to their line-ups forced upon them.

The potential for getting it wrong, for dismissing a serious concussion as just a bang on the head, is huge and real and with absolutely frightening consequences.

The medical argument for more time to make a safer judgment is almost irrefutable. Getting a replacement on while the decision is made – and getting him off again if the injured player shows no signs of long-term damage – makes sense.

The same applies for "stingers".

Collisions in and around the tackle are now so ferocious that quite often a player is momentarily incapacitated by a sharp, stinging pain to a shoulder, an arm, a leg, or sometimes his neck. While in many cases this pain dies down, almost completely, within the space of a couple of minutes, other quite similar pains are indicative of a deeper, more serious damage that will get worse.

The stinger can be worked through; the more serious pain needs immediate immobilisation.

Again medics are under pressure from all sides and have only a few seconds to get it right. Far safer, therefore – both for the injured player and the harassed medic – to put on a temporary replacement and take a bit more time to reach the correct decision.

But the game has just been rocked to its very core by this summer's Bloodgate scandal, when Harlequins first manipulated the rules regarding tactical substitutions and then cheated the rules regarding blood injury.

In the process of the subsequent investigations, it became very clear that they were not alone in twisting the regulations for tactical reasons.

Why then would anyone contemplate increasing the number of circumstances under which a coach can change his line –up? Why dangle more temptation to act, if not outside the letter of the law, then certainly outside the spirit of the game ?

Defenders of the idea of rolling substitutions stress again that player welfare is paramount. They also point to the success of the system in rugby league, where the total number of substitutions that a coach is allowed to make is 12.

Once he has reached that number he cannot replace a player- for any reason – and must continue with a depleted team.

But no player is going to want to leave the field if it means leaving his team a man short. In such circumstances he will stay on the pitch, run precisely the sort of risks that rolling substitutions are designed to eradicate, and will be expected to do so by both his coach and his team-mates.

But, say those in favour of the new measures, that will never happen because a coach will always keep a couple of substitutions up his sleeve so that he will never have to ask an injured player to soldier on.

Yet, in order to avoid that scenario at the end of the game, a coach risks encouraging it in the middle of the match. What if, for instance, the first half of the match has seen one of his team get a bang on the head, one a bloody nose and two receive "stingers"? If all recover, he has used eight of his 12 permitted substitutions.

Replace the front-row after an hour, as is the custom, and he can make only one substitution in the most crucial quarter of the game – the period when most injuries occur.

To avoid that, and to keep his powder dry for the match-defining moments, he'll have to instruct his players to play through injuries in the first part of the match – which is exactly what he does when there are no rolling substitutions. The proposal needs a lot more thought.