Ryder, who played only one T20 last summer due to injury and one to date this season, returned to the Stags early this year from the Essex county club in England where he reportedly already had a calf strain.
De Wet wasn't sure if the injury was a recurring one from England "but we just have to make sure we try to get him fit and ready because he's an important player for us".
"He was scheduled to play in our first match but he didn't pass the fitness test.
"It was hoped we would get him out for the second one and he didn't pass the fitness test.
"He got better ahead of the game at McLean Park but, unfortunately, it has aggravated the injury."
De Wet says CD Cricket is pleased with the way coach Heinrich Malan and his newly-appointed assistant, Englishman Ben Smith, have been going with the players in the T20 competition.
"We certainly seem to be playing a great brand of cricket," he says, also happy with the spectator turnout as the Stags came within a whisker of chasing down the highest domestic T20 total in the country against Otago Volts at Pukekura Park, New Plymouth, on Wednesday.
Malan says the 32-year-old former international's return to the batting crease depends on how he pulls up from rehab.
"We're taking him on a day-by-day proposition and as soon as he can compete and his fitness assessments are 100 per cent then he'll come into reckoning for selection," he says, clarifying Ryder's calf injury occurred during the Chapple Cup tourney in Napier in October.
Trying to chase 249 against the Volts in the one-run loss in an "unbelievable game", Malan says, was edifying in itself for his troops.
"The attitude we approached it with and the way we stuck in there, even from a bowling perspective ... so we're quite happy with the way we went about our business.
"These competitions go thick and fast, we're halfway through and we're really looking forward to the hit out tomorrow [today]."
The William Young-captained Stags, he feels, are still in a good position (second place on 14 points) after arriving in Hamilton yesterday to train.
However, today will be a different prospect against a Black Caps-heavy ND who have inherited the services of Trent Boult, Mitchell Santner and Tim Southee to add to Corey Anderson and Ish Sodhi's firepower after the two sides shared points in the round two, rain-abandoned match at Yarrow Stadium, New Plymouth.
Should Bruce shuffle up a rung or two will that use his prowess more efficiently, considering he's almost always not out with his fantastic strike rate?
"I think we've found a bit of a structure and blueprint for the way we want to play our cricket and everyone's bought into that from a team perspective," he says.
Malan says Bruce has a portfolio, like others, to fulfil.
If CD keep putting themselves in a position to win then players who perform will automatically catch the eye of national selectors.
The way the Stags have performed, be it the 12th or 19th over, reinforces the coaching staff's belief that the prototype doesn't need tweaking just yet.
"The way he [Bruce] scores runs and the way he's gone about it are raising a few eyebrows but we've spoken about it quite regularly that if you perform for your team and the side does well ... people will take notice," he says, mindful a few players have versatility and consistency to make national selectors reach prudent decisions.
"Bruiser's [Bruce] obviously put the numbers up on the board for a while but Will Young has done that for a long time and Seth Rance has done that," he says of red-ball batting specialist Young and seamer Rance, who is third equal on the top T20 wicket takers' list with seven, two behind on first-equal Brent Arnel and Tarun Nethula.