Wynne Gray: Welsh melt as substitutions turn up heat

It was astonishing from the All Blacks and demoralising for Wales who stayed in the scrap and were then blown off their own park. Photo / Getty Images

Substitutions are an inexact rugby science.

When Colin Slade came on for the All Blacks' final quarter push, his arrival seemed pre-meditated rather than a reaction to a specific issue against Wales at the Millennium Stadium.

This All Black panel bring repeat doses of intuition to their decisions and show how their judgment is as critical for continued success as the players' production.

The victim was Charles Piutau who was at his constructive and accurate best with Ben Smith and Julian Savea in a rejigged back three but was pulled from the last 20 minutes of the season.

As we pondered that puzzle and Slade's introduction at five-eighth, another layer of wonder arrived as he shelled an awkward low pass from Aaron Smith. The nationwide volume of concern would have filtered into the All Black coaches box in Cardiff.

With 10 minutes left the All Blacks were blinking at defeat, yet when the clock stopped they had surged to a 34-16 victory as the altered combinations slapped on four tries. It was astonishing from the All Blacks and demoralising for Wales who stayed in the scrap and were then blown off their own park.

Both sides rolled on their subs and while the All Blacks got plenty of bang from their bench, Wales collapsed.

They could not deal with the renewed tempo as their lungs and skills suffered under the pressure. Veteran halfback Mike Phillips and midfield back James Hook buckled from the bench as waves of All Black pressure washed over them.

They will say Leigh Halfpenny got a wicked bounce which sat up for Barrett's first try. No one will argue but the fullback was a single defender.

Wales were swamped. It was like watching a 400m runner go out strongly before withering in the final straight as rivals rolled past with their fitness and timing.

Halfpenny kept Wales in the test with his quality goal-kicking and there will be many in the valleys bemoaning the cruel late bounce which eluded him. They should remember the fullback's decision to run turnover ball out of his 22 soon after halftime which cost his side a try to Julian Savea.

They responded with a magnificent counter from halfback Rhys Webb but had given the All Blacks the chance to get to the flanks and show them where they had to attack as the game wound into its last stages.

When the heat went on, the All Blacks showed they were fireproof while the Welsh melted into the shadows which have engulfed the nation for the past 61 years.