Rolando McClain's comeback apparently did not get off to a smooth start.

The NFL Network, citing a source, reported that the retired inside linebacker showed up late for Tuesday's workout with the Baltimore Ravens and couldn't finish the team's conditioning test. He also reportedly failed to do any of the linebacker drills.

A team source told ESPN.com that it was a "tough day" for McClain.

McClain took to Twitter Tuesday night, apparently to address the workout:

No excuse for my failures. My success no apologies. I that I owe is absolute honesty. Keep it 100, but that's what they all say... #Hustle - Rolando McClain (@RMcClain205) April 16, 2014

McClain, the No. 8 overall pick in the 2010 draft by the Oakland Raiders, sat out last season after abruptly retiring a month after signing with the Ravens. He said he used the time to get his "priorities straight."

Earlier this month, McClain confirmed he was training for a return to the NFL and said he was "excited about the game again." Ravens coach John Harbaugh said the team would welcome him back if he proved that he had matured.

The Ravens are looking to improve their depth at inside linebacker. Daryl Smith is returning for his second season as a starter for Baltimore, and former second-round pick Arthur Brown is expected to replace Jameel McClain at the other inside linebacker spot.

The Raiders released McClain last April 5 after a series of off-field issues, including a shooting incident in December 2011 that led to McClain being charged with four misdemeanors. The charges were later dropped after he and the victim reached a financial settlement.

McClain signed with the Ravens five days after being released by Oakland but retired before attending even one practice. The Ravens still retain the rights for the 24-year-old former Alabama standout.

In 41 games over three seasons with the Raiders, McClain had 246 tackles and 6.5 sacks.