SANTA CLARA, Calif. (AP) This week's key phrase for Jim Tomsula: ''fine focus.''

The 49ers coach is calling for improved concentration to avoid more of the costly mistakes that have defined this down season for San Francisco (4-10), which fell behind by 21 points in the first half and lost 24-14 on Sunday to the playoff-bound Cincinnati Bengals.

Four turnovers, 11 more penalties, 2 for 14 on third down.

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''Penalties, negative plays, that's all a lack of focus,'' offensive lineman Andrew Tiller said Monday.

''All sides, we can control that. ... Basically just got to put down the pads. We'll do better on third down if we do better on first and second. Trying to convert on third-and-14, third-and-15 is hard.''

Now, the Niners must go back on the road with their 1-6 record away from Levi's Stadium to face the Detroit Lions on Sunday. They lost to the lowly Browns on the road Dec. 13.

Booed off their home field down 21-0 at halftime Sunday, some of the 49ers said they deserved it - including wideout Anquan Boldin: ''We're not fun to watch right now. Who wants to sit there and watch that?''

''We're a team and if we call ourselves a team, we have a bad game, it's our job to respond,'' linebacker NaVorro Bowman said.

''I challenged the whole team to respond to the last game we played. When you ask a man if you're going to rise to the occasion or fold, you expect to see them rise to the occasion.''

Yet, Tomsula has been pushing for such bounce-back performances all season and there has been little consistency.

The first-year coach sounded unaware Monday about remarks by CBS sideline reporter Jay Feely during the loss to Cincinnati pointing to Tomsula possibly sticking around for 2016.

''I had a chance to talk to Al Guido, the COO for the 49ers beforehand,'' Feely said Sunday during the broadcast. ''They knew what they were getting into when they had all the defections. (He) said they underestimated a little bit the impact that it had in the locker room, specifically the lack of leadership ... But I think they're confident with Jim Tomsula going forward.''

What that means for Tomsula's future is unclear, as CEO Jed York has said he would address any personnel matters at season's end - as was the case in late December 2014 when he announced the franchise was parting ways with Jim Harbaugh after four seasons and with one year remaining on his contract.

When it comes to the players missing, Tomsula acknowledges those key absences. Linebacker Patrick Willis retired, along with 16-year defensive lineman Justin Smith, and even linebacker Chris Borland after his standout rookie season.

Right tackle Anthony Davis also walked away from the game following a head injury late last year - perhaps not for good, though, he said - while franchise rushing leader Frank Gore departed to the Colts in free agency, while left guard Mike Iupati did the same and joined the division-leading Arizona Cardinals.

''There was a core group here with Justin and Frank. I was with all those guys the whole time. There was a core group here that built up through some tough times and got into some really good times and did a heck of a job leading and just the tightness,'' Tomsula said Monday.

''I don't think we've hidden from that. That core is gone. We're developing another core. We've got to develop a core. I think there's a lot of pieces to that core here. A lot of them are young.''

NOTES: RG Marcus Martin is in the league's concussion protocol after his fourth-quarter head injury Sunday. ... RB Shaun Draughn was undergoing an MRI on his injured knee that left Travaris Cadet as the eighth different running back to carry the ball this season.

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