Gill finished ninth in the world final last year and has thrown more than 21 metres this year. It appeared Gill's level of performance was on an upward trend.
"He was just starting to tick over. He has thrown further than I did at the same age and that's pretty good," said Walsh. "People were thinking he's not improving in the last few years but he was just starting to get things sorted and rolling for him."
Walsh, 25, said he had known for a few days about Gill's problems.
"It's a shame. It's one of those things you can't really see coming, and can't really stop either."
Walsh has a busy summer ahead.
He has put on "a bit of weight, and with that my strength levels have gone up as well, so everything's ticking along nicely".
Walsh plans to start his year at the Commonwealth Games trials at Hastings in late January. He'll have another competition in New Zealand before heading to the world indoor championships, where he'll defend his title at Birmingham, England from March 1-4.
After that he has events in Timaru, Christchurch and Auckland.
The Timaru event at Caroline Bay has special significance for Walsh, who was born and raised in the South Canterbury city.
"I remember years ago we used to do the steps up there, bounding up at the soundshell," Walsh said.
"We always said 'Jeez wouldn't it be great to have a shot put competition here'. You've already got the stand and we've already had a huge amount of support from businesses. People are pretty excited and it is the least I could do.
"I spent many years of my life in Timaru and to take something back like an international competition, but also a community event, is going to be a real fun night."
Walsh is hoping a quality field, with a distinctly Commonwealth feel to it, will line up.
Last year, Walsh attracted top-flight Americans Ryan Crouser and Joe Kovacs to events in Christchurch and Auckland.
This time Jamaican O'Dayne Richards ranked 10th, and who beat Walsh to the Commonwealth Games gold with his final throw in Glasgow three years ago, former world champion and good mate Ryan Whiting, a two-time world indoor champion, and Canadian Tim Nedow, who took bronze in the same final, are coming along with a clutch of Australians and two South Africans.