SURPRISE, Ariz. -- The Cubs came into this spring with an increased confidence in their rotation depth. Between the established arms in place, the big offseason signing of Shota Imanaga and a group of younger players on the rise, Chicago feels it has the pieces to help withstand setbacks.

That is already being put to the test.

On Sunday morning, Cubs manager Craig Counsell noted that veteran right-hander Jameson Taillon might not be ready for Opening Day. Even if the pitcher’s lower-back injury does not turn out to be a serious ailment -- Taillon was set to undergo further testing to determine the extent of the issue -- the development could have an impact on the pitching staff.

“Look, you never want to lose a player. You never want to even consider it,” Counsell said. “I don’t think this is a long-term absence for Jamo, so it’s not really one of those concerns. But, I think this is what’s expected. I think we’re in good shape.”

How does this impact the rotation?
The Cubs plan on handing the ball to lefty Justin Steele for Opening Day. Behind him, the North Siders have veteran Kyle Hendricks and Imanaga -- the latter joining the fold via a four-year, $53 million pact over the winter. Taillon was set to be the fourth lock for the starting staff, but his comeback could linger into the season.

Prior to Taillon’s lower-back injury -- one that flared during his warm-up routine on Saturday and led to him being scratched from his planned Cactus League debut -- the last rotation spot was up for grabs between Javier Assad, Drew Smyly, Hayden Wesneski and Jordan Wicks. Sans Taillon, two from that group could now be in the Opening Day cast.

Smyly (3 1/3 scoreless innings with four strikeouts and one walk) and Wicks (one unearned run allowed with seven strikeouts in 4 1/3 relief innings) both pitched in Sunday’s 5-1 win against the Rangers.

“We’ve got a bunch of guys still stretched out and ready to keep going,” Counsell said. “We have not ruled anybody out at this point. So, we’ll just keep a bunch of guys stretched out and see how that plays out.”

It is also worth noting that Counsell wants to maintain flexibility with the back of the rotation, allowing for additional days off for members of the staff. That includes Imanaga, who is adjusting to a five-day routine after being on a six-day program in Japan. Counsell has described the situation not as a six-man rotation, but maybe working in a sixth starter on occasion.

Assad, Wesneski and Wicks all have Minor League options, so they could shuttle between Triple-A Iowa and Chicago as needed. Smyly is also versatile enough to move between rotation and bullpen. Plus, the Cubs have three off-days within the first 15 days of the season, helping the team space things out for the rotation.

Could this alter the bullpen structure?
The main way the Taillon situation could impact the bullpen would be if the Cubs determine that Smyly should stay in the rotation. That would reduce the number of locks for the relief corps to five: Yency Almonte, Adbert Alzolay, Mark Leiter Jr., Julian Merryweather and Héctor Neris.

While Assad, Wesneski and Wicks could, in theory, be options for the bullpen, Chicago’s desire to maintain rotation depth at the front end of the season likely means the odd men out open as starters for Triple-A Iowa. If one did land in the bullpen, Assad would probably be the pick.

If Smyly slots into the rotation, there could be as many as three relief spots up for grabs. The list of candidates on the 40-man roster includes Jose Cuas, Luke Little, Daniel Palencia and Keegan Thompson. The remaining non-roster candidates include Colten Brewer, Carl Edwards Jr., Edwin Escobar, Richard Lovelady, Thomas Pannone and Cam Sanders.

Is Counsell factoring in handedness?
The Cubs already have a pair of lefties in the rotation (Imanaga and Steele) and two more southpaws (Smyly and Wicks) in the hunt for a starting job. In the name of balance, it seems unlikely that Chicago would feature a rotation with four left-handers.

Asked about such a scenario, Counsell said: “I think of it as, ‘Who are the best people to get hitters out?’ It doesn’t have anything to do with [being] left-handed or right-handed. Who’s going to get people out the best? That’s who’s going to pitch.”

If Smyly stayed in the rotation, the Cubs’ lefty bullpen options right now include Little, plus Escobar, Lovelady and Pannone from the non-roster group. The North Siders have NRI contenders on both the pitching and position player side, but the current 40-man roster would make it challenging to add multiple players in that group for Opening Day.