The midfielder attracted criticism from Gers fans last term following a string of below-par performances in the Third Division.
Black has been an integral part of the Ibrox side that has started the League One campaign in stunning fashion, however, with Ally McCoist's side bidding for their ninth straight success at Brechin today.
And assistant manager McDowall is delighted to see the former Hearts star shining in Light Blue.
He said: "I keep making this reference, when I'm asked this question. When Kevin Thomson and Steven Whittaker came to us from Hibernian, they didn't settle here for about a season.
"Where they were fortunate was that they had guys around them who were top international players, they could carry them.
"Wee Ian Black came in with kids from the youth team.
"Finding out how to settle into a place like this is difficult when you come from a Hearts or Hibs, no disrespect to these clubs.
"That's where I felt for these boys who came in, players like Black and Dean Shiels, who got a lot of stick last year for not being the players that everyone thought they were. The same went for David Templeton.
"Well they needed time to settle, as well. And they won the league by 24 points, which was fantastic, plus they've settled in now.
"We've added some more experienced players and they're enjoying that. Because, if they're not having a great day, they might find that Nicky Law has taken up the mantle.
"That's what happens, some days it's not there, you just have to work hard and hope for somebody else to do the turn."
Rangers could be without defender Lee Wallace for the Glebe Park clash this afternoon following his withdrawal from the Scotland squad that beat Croatia in midweek with a knee injury.