Biggest Takeaways from San Francisco 49ers' Week 15 Loss

First big takeaway from the San Francisco 49ers' Week 14 loss to the Cincinnati Bengals: Fans are mad.

A group of fans paid money to fly a banner that said "Hold Jed Accountable" over Levi’s Stadium before the game. Three weeks ago, before the previous home game, fans paid to fly a banner that said "Jed & 49ers should mutually part ways."

These banners are just one indication of fan outrage. Another indication? Empty seats. The stadium looked half-full for most of Sunday’s game and almost entirely empty near the end of it.

Boycotting home games and flying anti-York banners are two good ways to hold team CEO Jed York accountable. He may have to make changes if the outrage continues.

Here are five more takeaways from the Niners’ 10th loss of the season.

The 49ers Have a Good Young Core on Defense

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The 49ers lost five leaders from last season’s defense: Justin Smith (retired), Patrick Willis (retired), Aldon Smith (released), Ray McDonald (released) and Antoine Bethea (injured).

This lack of leadership is a big reason the defense has played so poorly away from home this season. Inexperienced defenses tend to play poorly on the road.

At home, the Niners defense has been fantastic. A quality young core of players has emerged, including free safety Eric Reid, strong safety Jaquiski Tartt, slot cornerback Jimmie Ward, outside linebacker Aaron Lynch, defensive end Arik Armstead, nose tackle Ian Williams, defensive end Quinton Dial and outside linebacker Eli Harold.

The defense will play better on the road as these young players gain experience and mature into leaders.

The 49ers Lack a Good Young Core on Offense

Tony Avelar/Associated Press

Unlike the defense, the 49ers offense plays as bad at home as it does on the road. Hey, at least it’s consistent.

San Francisco has no young core of players to build around on offense. It has busts, such as guard Marcus Martin, tight end Vance McDonald and guard Brandon Thomas. The only talented young player on offense is running back Carlos Hyde, who finished his first two NFL seasons on the injured reserve list.

The Niners have to completely rebuild their offense—we’re talking new skill players, new offensive linemen, new quarterback, new everything. Can general manager Trent Baalke find the right guys, or does his expertise lie in defense only?

Eric Mangini Is a Predictable Play-Caller

Eric Risberg/Associated Press

With two minutes left in the second quarter and the Bengals facing 3rd-and-1 from the Niners 8-yard line, defensive coordinator Eric Mangini called a strong-safety blitz, which failed.

Cincinnati’s running back blocked the blitzer, and AJ McCarron completed a seven-yard pass to Marvin Jones. Cincinnati scored a touchdown on the next play.

Two plays later, after Vontaze Burfict intercepted Blaine Gabbert, the Bengals had the ball in the red zone once again. On the first play of that series, Mangini called the same strong-safety blitz he had called about a minute earlier.

Bengals offensive coordinator Hue Jackson was ready for that blitz. So, he called the perfect play to defeat it—Y crease. Tight end Tyler Croft ran up the seam into the space the blitzing safety had vacated and was wide-open when he caught the touchdown pass.

Can you say predictable?

Geep Chryst Is a Conservative Play-Caller

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Even though he almost never succeeds, 49ers offensive coordinator Geep Chryst is determined to establish the run.

No matter the running back, Chryst spends the first quarter of practically every game running the ball on first and second down and then going three-and-out.

While he’s doing this, the Niners tend to fall behind. By the time Chryst establishes the run and the play-action passing game, the Niners often are too far behind for Chryst to use either one.

The Niners need a more aggressive offensive coordinator, someone who can create an early lead instead of an early deficit. San Francisco has not scored one offensive touchdown in the first quarter this season.

Blaine Gabbert Is a Backup Quarterback

Tony Avelar/Associated Press

Blaine Gabbert does certain things well.

He speaks clearly and loudly in the huddle. He calls plays at the line of scrimmage before the play clock expires. He scrambles. He throws a mean checkdown pass. And, he’s polite during his press conferences.

That’s about the extent of his good qualities.

Bad qualities: He is content to punt. On third down, he’d rather complete a short pass to the running back than throw past the first-down marker. The Niners have converted just four of 27 third downs the past two games.

Gabbert is a backup quarterback and a good one. He won’t lose many games with boneheaded mistakes. But, he won’t win many games, either.

The Niners need to draft a quarterback who can compete with Gabbert for the starting job in 2016.

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All Levi's Stadium observations obtained firsthand unless otherwise noted.