But a new ball and putter combination paid instant dividends as the 41-year-old Englishman claimed a share of the clubhouse lead in the Aphrodite Hills Cyprus Open.
McEvoy carded a second successive 66 in the inaugural edition of the £900,000 event to join Scotland's David Drysdale and Finland's Sami Valimaki on 10 under par before play was suspended due to fading light.
McEvoy had missed the cut in four of his last five starts and began the week ranked 1,258th in the world, but carded six birdies and a solitary bogey in pursuit of his second European Tour title.
"My results probably haven't shown my actual overall game," he said. "I've been playing okay, but the results have been pretty poor. Putting's been a very weak point in the last couple of months.
"I've changed putter this week, which has been good for confidence, and I've also done a ball change this week as well. I did some testing and just found that the ball was dropping out the sky really quickly with the cold weather, so I decided to try something else and it seems to be working really well."
While US Open champion DeChambeau – who apologised for his brief handshake with McEvoy after making a triple bogey on the 72nd hole of the European Open – has successfully transformed his game through massive hitting, McEvoy believes chasing distance was a big mistake.
"Over the last couple of months I sort of felt like I lost my identity a little bit," added McEvoy, who ranks 146th on the European Tour in driving distance.
"I was trying to hit the ball too hard, I was trying to hit it further and I didn't really need to. I kind of lost where I was going with my game and I needed to back off it a little bit, sit down and look at where I was going wrong and start doing what I was good at again.
"I just said to myself 'I don't need to be hitting it 30 yards further, 10 yards further would be a massive increase for me'. If I get it on the fairways then I've got a chance of getting it close on the greens and giving myself chances."
Drysdale was annoyed to bogey the 18th after a "pathetic" short-range par putt came up short of the hole, but a second round of 67 left him well placed to contend for a first European Tour title at the 509th attempt.
"There's a lot of golf to be played," added Drysdale, who lost a play-off for the Qatar Masters in March.
"I haven't had that many opportunities over my career. I'll give it a crack over the weekend and see what happens."