Though many expect C.J. Beathard to improve in his second year in Kyle Shanahan's system, it is generally accepted that a lot will need to go right for the San Francisco 49ers to have success with him at quarterback in the wake of Jimmy Garoppolo's season-ending ACL tear.

The Niners will need their running game to continue to perform at a level that has them second in the NFL in yards per game on the ground. Improved pass protection will be required from an offensive line that has made strides as a run-blocking unit but has already given up 13 sacks, and the Niners can ill-afford the drops that have hindered the offense in the opening three weeks.

However, the biggest boost Beathard could receive is some consistency from the defense, which has enjoyed at best mixed fortunes through three games.

The defensive numbers, for the most part, do not make for pretty reading. San Francisco ranks 26th in overall defense and is 25th in Football Outsiders DVOA on that side of the ball. The Niners are 27th in the NFL in passing yards per game and 29th in pass defense DVOA.

It is a different story against the run. The 49ers rank ninth in the league in rushing yardage given up and are eighth in run defense DVOA. The contrast in their play against the pass and the run is fitting for a defensive unit that has yet to string together a complete performance in 2018.

San Francisco's defense has impressed only in spurts. The Niners held Kirk Cousins and the Minnesota Vikings offense to 17 points in the opener in what has so far been the standout display by Robert Saleh's group. In Week 2, however, a performance that saw the Niners hold the Detroit Lions to 13 points through three quarters was not maintained as the defense almost surrendered a 17-point lead. The opposite happened last Sunday as the Chiefs put 35 points on the 49ers but just three in the entire second half as San Francisco threatened a comeback.

That kind of inconsistency speaks to the inexperience of a young defense with little history of finishing games. Yet, though this group has numerous issues in need of fixing, the talent is there for the defense to put together a complete performance.

The secondary appears to be a huge weakness, particularly with Richard Sherman expected to be out a couple of weeks with a calf injury, and missed tackles have also developed into a substantial problem. Still, between the outstanding level of depth on the interior defensive line and the partnership between Fred Warner and Reuben Foster at linebacker the 49ers have a potentially great front seven.

Flashes of such greatness have been intermittently apparent, but the prospect of the defense -- and specifically the front seven -- realizing its potential does not look to be on the horizon, making Beathard's task even tougher.

Until he proves otherwise, the assumption will be that Beathard does not have the ability to keep the Niners in shootouts as Garoppolo does. Every area of the team will need to step up for the 49ers to come out of the disappointment of losing Garoppolo with a competitive record. For the defense that has to mean finding consistency. Saleh's group was expected to make strides in 2018, instead its performances have been spotty at best. Now without a quarterback who seemed capable of keeping San Francisco in any game, the 49ers have to find a formula for a 60-minute defensive performance.