The contents of the magazine also changed, a books column was added, there was discussion and reviews of the best outdoor equipment etc. The fiction was kept intact, though.
We've discussed earlier whether this was the cause for Arthur Hoffman's departure from the magazine. Walker Martin (see the comments in the link above) feels that Hoffman was supportive of the move, but left because it failed to improve the business. I felt the new ownership was taking it in a direction that Hoffman didn't want, and that was part of the reason that Hoffman left.
Here's something that I found recently that might help - correspondence between Joseph Cox, the editor who succeeded Hoffman and Horace Kephart, an outdoors expert. Cox wanted Kephart to become a part of the Ask Adventure group of experts who answered readers' queries.
While doing so, he mentions that the new ownership wanted to make Adventure into the "trade journal of all the outdoors". That would probably have meant less fiction and more non-fiction. That change in direction, combined with the drop in readership, was (in my opinion), the reason for Hoffman's departure.
As we know, the magazine's circulation didn't improve and Adventure was back in pulp format in 1927. Joseph Cox left as editor in 1928 and the magazine went downhill until Harold Bloomfield took over as editor in 1934.