But the unlucky full back should not be allowed to shoulder the blame for the defeat alone, for the Reds had enough chances, especially in the first quarter of the match during which they forced 11 corners, to have won fairly comfortably.
As it was, Alfreton's inability to put the ball in the net made McFadzean's agony all the greater to bear.
Manager Nicky Law made changes after the Reds' failure to hit the target against Barrow. The return of skipper Tony Butler meant Rob Pacey drew the short straw and dropped to the bench.
Meanwhile Mark Barnard was restored to the starting line-up at left back with Anton Brown on the left of midfield so that Danny Reet could partner Paul Clayton up front, meaning that Brian Cusworth also had to settle for a place on the bench.
Hinckley included Leigh Platnauer who, less than a week earlier, had skippered Gresley Rovers in the Derbyshire Senior Cup tie at the Impact Arena, and also Callum Lloyd who had a spell at Alfreton on loan from Mansfield last season, but is now permanently with the Leicestershire club.
The game could not have started any worse for Alfreton. Tom Bonner's cross from the right by-line flew across goal and McFadzean, in trying to clear under pressure from Billy McKay, succeeded only in turning the ball past Kyle Sutcliffe.
The Knitters might have gone two up with the game still less than four minutes old, when Brian Quailey pulled a good chance wide.
From then on for the next 19 minutes it was one way pressure on the home goal. Twice keeper Sean Bowles had to punch away to clear his lines, first under pressure from Barnard's corner, and then again as Steve Warne played Clayton through.
The best chance came in the 14th minute. Clayton tried to stab the ball over the line in a scramble despite being on the ground, Quailey hacked that one behind for a corner, and when Barnard's flag kick was played to McFadzean he crossed low into the box,from where Clayton's full-blooded volley was blocked by Charlie O'Loughlin for another corner.
Hinckley broke out of their rearguard action in the 23rd minute with Gez Murphy going clear on a dangerous run but Dominic Roma screwed the cross behind with the Reds defence stretched.
And it was the Knitters' turn to go close again in the 32nd minute with Bonner denied by a post after McKay's free kick caused problems in the area.
Three minutes later Quailey fired too high from 20 yards, before a vital challenge by Butler and Brown robbed the United forward as he was about to pull the trigger onto Roma's run and pass.
If the Reds had gone off the boil after the midpoint of the first half, the game turned drab for both after the break.
Warne made a strong run across the 18-yard line 11 minutes in but his weak shot was easily held, then Clayton was too high following Josh Law's determined run and cross.
Cusworth replaced Reet, who has not made the same impact on the side since his return from suspension, and when the substitute headed Warne's cross on, McFadzean took careful aim in a bid to atone for his own goal as the ball bounced, but his attempted struck Clayton.
Another header on by Cusworth set up a chance for his former Parkgate strike partner but this time Clayton's ferocious drive was just the wrong side of the angle..
Bowles did well to hold a difficult bouncing ball from McFadzean's punt through as Cusworth challenged in the 73rd minute.
But the next 20 including stoppage time were lost in midfield with few openings and the ball spending too much time in the air, as Hinckley were content to sit on their one goal lead.
However, in the fourth added minute Bowles made a tremendous save to preserve his side's win as Cusworth burst through and let rip from 15 yards.

HINCKLEY: Bowles, Roma, Platnauer, Bonner, O'Loughlin, Byron (Hoyte 59), Lloyd, Richards, Murphy (Edwards 79), Quailey, McKay. Subs not used: Gundelach, Storer, Belford.
ALFRETON: Sutcliffe, McFadzean, Barnard, L. Wilson, Butler, M. Wilson, Law, Warne (Walton 89), Clayton, Reet (Cusworth 59), Brown (Bowler 83). Subs not used: Pacey, Matthewson.
REFEREE: Peter Grove of Stourbridge.
ATTENDANCE: 405.
GOAL: Hinckley – McFadzean og 2.
CAUTIONS: Hinckley – McKay 11 (foul on McFadzean); Quailey 29 (foul on Sutcliffe); Richards 79 (foul on McFadzean). Alfreton – Brown 48 (foul on Richards); L. Wilson 90+1 (foul on Edwards).
REDS MAN OF THE MATCH: Paul Clayton