The offseason leading up to free agency and the NFL draft is generally an exercise of roster evaluation. But answering the question of why? a team needs a cornerback or left guard tends to get oversimplified.

Yes, it’s been written about in this space (and many others) the 49ers have needs at corner, pass rusher and interior offensive line while continuing to add depth throughout the 53-man roster.

But it’s time we take a closer look at why they have those needs. Specifically, the areas of the game San Francisco struggled with that led directly to losses last season. Understanding the value of an antidote means reverse engineering through the symptoms.

Here are five areas the 49ers struggled with during the 2017 campaign and that need to be improved to be considered a playoff contender next season.

RED ZONE

(Joe Robbins/Getty Images)

Key numbers (ranking):

-Opponents scored touchdowns on 59.7 percent of red zone attempts (26th).
-49ers found the end zone on 47 percent of red zone trips (27th).

The 49ers struggled in this area on both sides of the ball. Defensively, their situational play in the red zone (and on third down, which we’ll touch on later) proved they need to upgrade the pass rush and at cornerback.

Offensively, the 47-percent red-zone clip for the year was actually higher than the five games Jimmy Garoppolo started to finish the season. He helped the 49ers score touchdowns on 11 of 24 red zone trips over that span (45.8 percent). That was weighted heavily be the team’s 0-for-5 performance in Garoppolo’s first start against the Bears.

Over the final four games, the 49ers scored touchdowns on 57.9 percent of their trips, which would have ranked ninth in the NFL paced out to an entire season. So the 49ers may be close to taking a drastic step toward improving in this area based on a quarter-season sample. They’ll need their young skill players – Trent Taylor, George Kittle, Matt Breida, et al – to continue developing while the offense gets more cohesive with Garoppolo entering Year 2 in Kyle Shanahan’s system.