The rumors started coming out earlier today:

#Oregon DB Terrance Mitchell is making final preparations to enter the NFL Draft, according to multiple sources. — Rand Getlin (@Rand_Getlin) January 3, 2014

Rob Moseley wasted no time in getting to the bottom of the issue:

Just got off the phone w/ Terrance Mitchell, can confirm he's entering the draft. Said he loves UO and its fans but wants to take next step. — Rob Moseley (@DuckFootball) January 3, 2014

And just like that, three quarters of our starting secondary is gone (with Avery Patterson and Brian Jackson leaving via graduation). There is no word from Ifo Ekpre-Olomu yet, though he is rumored to be contemplating leaving as well.

Unlike Ifo, Mitchell is not a first round pick in most draft projections, but he is widely respected as one of the best corners in the conference, and has very little left to prove at the collegiate level. Mitchell finished the season with five interceptions, seven pass breakups and 59 tackles. The three year starter played in 40 games over his Oregon career. Troy Hill and Dior Mathis will be first in line to replace him next season.

De'Anthony Thomas and Ifo Ekpre-Olomu are players who could enter the NFL draft who have yet to announce decisions.

UPDATE:

It appears that Mitchell didn't get the best evaluation from the NFL:

Though he requested an evaluation by the NFL draft board, Mitchell said he did not read much into a review he did not consider favorable. "It wasn't a fair evaluation," he said. "It came back in like a week and they didn't have time to break down film. They didn't get chance to really dissect what was real. I've been an underdog my whole life.

While I wouldn't think Mitchell is in any danger of going undrafted, it sounds like he's going to need a good combine to improve his stock.