Australia captain Michael Clarke and England counterpart Alastair Cook have played more than 200 Tests between them but both are perplexed by the to-and-fro nature of this season`s Ashes series.
England won the first Test in Cardiff by 169 runs only for Australia to bounce back with a mammoth 405-run victory in the second Test at Lord`s.
Then England responded with an eight-wicket win inside three days in the third Test at Birmingham`s Edgbaston ground last week.
As a result, England take a 2-1 lead into the fourth Test of a five-match series at Nottingham`s Trent Bridge ground starting on Thursday.
"I can`t explain that -- it`s a rollercoaster ride," Clarke told reporters on Wednesday.
"We played some not so great cricket at Cardiff and Edgbaston and then, at Lord`s, we were outstanding.
"We have seen that from both teams. I don`t know the reason."
Cook perhaps got closest to an explanation by observing how a team that had taken an early advantage in a match had retained a strong position until the end of the game.
"When both sides got on top, they`ve been pretty ruthless at staying on top and not allowing the other side to come back," Cook said.
Cook, whose side will look to break a seven-Test streak of alternating wins and losses by recording their first back-to-back victories of 2015, added: "I`ve seen a shift from one side to the other side taking the lead, but I haven`t seen it shift back and forward in three games like this. Hopefully, that can stop."
No side since Australia were inspired by batting great Don Bradman back in 1936/37 have come from 2-1 down to win the Ashes, with Bradman`s side 2-0 down at one stage.
But Clarke said his team could record a landmark achievement of their own this Ashes.
"We showed that at Lord`s," he said. "We can take confidence that we bounced back after Cardiff... we`ve got to have the same attitude now."