Moody's Analytics chief economist Mark Zandi said technical issues may have made ADP's report on the April job market look much stronger than it actually was.

Earlier Wednesday, ADP's report with Moody's said private sector hiring hit an eye-popping 275,000 in April, just about 100,000 more than expected.

But Zandi said on CNBC shortly after the release that technical factors may have inflated the number.

He later detailed three components that go into the ADP number that were unusually volatile or out of line. One was a very low reading of ADP's own payroll data. Another was the very low level of unemployment claims during April, which reached a 50-year low. The third was the high level of volatility in the Bureau of Labor Statistics' recent monthly jobs data.

In ADP's press release, Zandi said the number overstates the strength of the economy.

"Bottom line, I don't think it's going to come in at 275,000. My sense is its going to come in pretty close to consensus 175,000 to 200,000," he later said in a telephone interview.

ADP's payroll number sometimes tracks close to the actual government nonfarm payroll report, and sometimes not. Still, it is monitored by Wall Street as one metric to watch ahead of the monthly jobs report, typically released two days later.