The big striker has had his doubters during his 18 months at Fir Park, but claimed his second hat-trick of the campaign in Sunday's 3-2 win against St Johnstone.
This matched his 16-goal haul for the whole of last season and returned Well to joint-second in the SPL.
While McCall admits that Higgy, much like Boyd, will never be seen as someone of athletic virtue, the Steelmen boss says his finishing is more than enough to make up for it.
He said: "Higgy does have the same level of importance to Motherwell (as Boyd did at Rangers). We know his value in the dressing room and the quality and number of his goals has been vital to us this term.
"Much like Boyd, Higgy is never going to be accused of running away from anyone. But for a big man he has superb technical ability, holds the ball up really well and the quality of his finishing is there for all to see.
"I have lost count of the number of times that opposition managers have come up to me after games and said how difficult he makes life for their backline.
"We have to be honest and say that against St Johnstone he was the difference. I thought he was just very clinical and he's the same on the training ground every day."
Amazingly, there has been no interest for the Well top scorer, who is out of contract at the end of the season.
McCall said: "We have a few players who are out of contract this summer and hopefully we can get things nailed down over the next few weeks with them.
"But so far we have had no enquiries and hopefully it stays that way."
When it comes to adding to his squad, McCall admits that the signing of Kallum Higginbotham last week, who missed out on making his debut on Sunday against Saints, will be the only new arrival.
The Fir Park gaffer said: "We will go with a squad of 20 and hopefully that will be good enough.
"There is no room to go for any loan moves for anyone else and if no-one leaves after Jamie Murphy, then we will stick with what we have."
Well have the weekend off before returning to action with the visit of Dundee United a week tonight in a game that was originally scheduled for the following day.
McCall is determined that his men will use that fixture as an opportunity to reverse their last home loss, which was to United, also in a midweek home game, back in November last year.
The Motherwell gaffer said: "That was one of our most frustrating performances of the season because the only thing that was wrong with the game was the ball somehow stayed out the net.
"But we are six home SPL games unbeaten and determined to keep that momentum going."