Even if their heads might be spinning, the Texans quarterbacks say they're enthused about the new offense.
"It's a very productive time for us, just because of all the new things that are going on out there," Ryan Fitzpatrick said.
Case Keenum, who started eight games in 2013, said he likes the offense as well.
"I think it's going to be good," Keenum said. "It's going to be suited to fit whatever guys we have that can play."
T.J. Yates, who guided the Texans to a playoff victory in January of 2012, is excited about the freedom given to the quarterback in the new system.
"If you like a certain thing here, you want to signal a route to a guy, or you kind of just want to take control, there's lots of options that you can have in this offense," Yates said. "Lots of places to go. It's a matchup offense. You like a match up with a guy here, you can go there. We got a lot of players on this team that we can take advantage of it then."
Yates played collegiately at North Carolina, where the Tar Heels operated an offense very similar to what was run under former Texans head coach Gary Kubiak. Yates described the new offense as a "polar opposite" to the one he's played for the last seven years.
Fitzpatrick, Keenum and Yates have about a month's head-start on rookie Tom Savage, who cited brainpower as a necessity in O'Brien's system.
"You gotta be smart," Savage said. "You gotta know everything. Whether it's the looks the defense is giving you. Where people on your side are supposed to line up, everything."
For the most part, O'Brien has been pleased with what he's seen from the four quarterbacks.
"They're all doing a good job," O'Brien said Tuesday. "It's not easy to learn a new offense, especially when you've been around awhile. I've seen a lot of improvement every day with that whole group."
The Texans took part in Day 2 of OTA's Wednesday morning at the Houston Methodist Training Center.
While digesting the new formations, plays, verbiage and terminology might be complicated, Keenum said the ultimate job of the quarterback running O'Brien's system is very simple.
"The job as a quarterback is to get the ball out of our hands in whatever way that is," Keenum said. "Run, pass, get it to the guys who can make plays."
The Texans wrap up the week of OTA's tomorrow, before starting back up on Monday.