Often the most frustrating sports stars are the ones with extraordinary talent; the ones who blow so hot and cold that supporters are left almost constantly confused.
Stuart Broad is one such performer: a cricketer of incredible quality, but of perplexing inconsistency. It is never the average players who infuriate, but the prodigious ones.
As with seemingly every high-profile series, the 27-year-old was virtually anonymous for the majority of the contest with many critics again slipping back into the trap of calling for him to be dropped or rested.
But then, predictably, he produced a quite breathtaking response with 11 wickets at Chester-le-Street including six in an astonishing and pulsating evening session to win England the match and the Ashes outright.
It's hard to overstate the fact that Broad effectively won the fourth Test for England single-handedly on the fourth day - Ian Bell had starred earlier in the match with a third century in the series - with his heroics as his inspired spells left Australia in tatters.
What makes Broad so frustrating is his immense talent as an all-round cricketer, not just as a bowler. His batting has been famously described as "Sobers-esque", but his performances have been constantly underwhelming and he has failed to fulfil his potential.
His Test averages of 30.50 with the ball and 24.94 with the bat are, let's not understate this, hugely disappointing. They do not, in any way, do justice to the ability that he has in either aspect of the game.
Even prior to the fourth Test in Durham, many were calling for Broad's head with his six wickets at 54 runs apiece a poor reflection of a tremendous talent in favourable home conditions.
But, as ever, the mercurial Broad delivered a spell of quite unbelievable potency which saw the paceman dramatically transformed once more from a perceived under-performing whinger, to the hero that clinched another outright Ashes series triumph.
It has always been this way for the Nottinghamshire bowler. Lean spells aplenty, but his sensational spell of bowling in the fifth and decisive Ashes Test at The Oval in 2009 will always be recalled as yet more proof of his match-winning ability.
With the series in the balance, Broad claimed figures of 5-37 in 12 overs, including 4-8 in 21 balls, and from that moment on the series belonged to England. So it was hardly a surprise when he sprung to life when it mattered most in this series.
As Cook said of Broad amid the celebrations in Durham: "Words can't justify how good a spell of bowling that was. It was a fine spell of bowling. That's probably not the right adjective either.
"As a captain and knowing how important how that session was - if we lost that session we would have been struggling. Broady knew that and the lads knew that. He really charged in. When everything clicks and bowling in the high 80s with the control Broady has it's incredibly hard to bat."
That will always be the perennial frustration with Broad: how good would he be if he could only find a way of producing such performances more consistently? How special would he be if he worked harder on his batting and justified his talent as a potential all-rounder?
Australian journalist Malcolm Knox in the Sydney Morning Herald perhaps summed Broad up best after the fourth Test: "He can spend long periods bowling dreck, as a Test career average of 32 and strike rate of 62 suggest, but when thrown the ball and asked to win a Test match, he has the knack. Is there anything a captain values more?"
England may just have to accept that, while he may test the patience for extended spells repeatedly in a strangely up-and-down career, the highs are certainly worth waiting for.
They may never cease to frustrate, but special talents such as Broad will always be worth persevering with.
His innings figures in this series tell their own story - it's all or nothing for the England star:
1-40 - Trent Bridge, first innings
2-54 - Trent Bridge, second innings
1-26 - Lord's, first innings
0-54 - Lord's, second innings
1-108 - Old Trafford, first innings
1-30 - Old Trafford, second innings
5-71 - Chester-le-Street, first innings
6-50 - Chester-le-Street, second innings