The 49ers were dealt a huge blow this past Sunday when franchise quarterback, Jimmy Garoppolo, was lost for the season after sustaining a torn ACL against the Kansas City Chiefs. Garoppolo was the primary reason for the optimism surrounding the 49ers after leading the team to five straight wins to end the 2017 season.

On top of Garoppolo's return and contract extension, the 49ers went out and signed Jerick McKinnon, Richard Sherman, Weston Richburg and drafted Mike McGlinchey to be starters. All players were considered "upgrades" over the starters they replaced.

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The 49ers then became trendy picks to make the playoffs and potentially compete with the Los Angeles Rams for the NFC West division title. The season couldn't come soon enough, as this was the most excitement the franchise had experienced since the Harbaugh era.

Then, things came back down to earth. The 49ers' prized offensive acquisition, Jerick McKinnon, tore his ACL in practice after sustaining a leg injury earlier in Week 1 of the preseason.

On top of that loss, the 49ers looked sluggish and mistake-prone leading up to the season. The team consistently committed drops and penalties, and didn't look like a team that was ready to make a playoff run.

This type of play continued into the regular season. The 49ers started slowly against the Minnesota Vikings and could never recover. The George Kittle drop and breakdowns on defense epitomized the mistakes that led to the 49ers 24-16 loss to the Vikings.

Even in a win against the Detroit Lions, the 49ers didn't look right. The team took a 30-13 lead late in the game and nearly blew that lead and lost the game. The defense looked lost and confused, Garoppolo and the offense couldn't finish. The 49ers were lucky to salvage a 30-27 victory to go 1-1 on the season.

Much of the same play on defense occurred against the Kansas City Chiefs in Week 3. The 49ers' defense allowed five touchdowns in the first half, including three touchdown passes by the first-year starter, Patrick Mahomes. The team was down 35-10, but at least they still had Jimmy Garoppolo.

Everything changed in one unforgettable play. A play that has changed the entire outlook for the rest of the 2018 season that resulted in Garoppolo tearing his ACL and being out for the year.

The quarterback depth chart now begins with CJ Beathard being the starter and former practice squad quarterback, Nick Mullens, as his backup. The duo could arguably be the worst quarterback tandem in the league on paper.

Garoppolo wasn't perfect. He missed easy throws, such as one to Kittle in the end zone against the Vikings and another to Pierre Garçon last week against the Chiefs that would have gone for a huge gain.

But Garoppolo made enough plays for this team to be able to win even with his mistakes, and we are about to find out how important of a piece he is to this 49ers' team.

This is just the second year of what looked to be a long-term rebuild before acquiring Garoppolo. And this 49ers' team as a whole has looked, at times, like it's stuck in that same rebuilding mode.

The 49ers lead the league in missed tackles over the first three weeks, are near the top of the league in penalties with 26 of them for 254 yards, and have struggled on defense overall.

Beyond that, the team may not have as much talent and depth as initially thought heading into the season. All three levels of the defense have been hit with injuries but have struggled regardless.

Safeties Jaquiski Tartt and Adrian Colbert were in line to take a forward leap, but have either been injured or have played poorly. Sophomore cornerback, Ahkello Witherspoon, was another player who was projected to develop further. But he was benched against the Detroit Lions in the second half and did not even start last week against the Chiefs.

On the defensive line, starters Solomon Thomas and Arik Armstead have been underwhelming. Frankly, Thomas should be playing "Big End" and is arguably out of position at LEO for the 49ers' defense. Armstead may be a trade candidate at this point and could have some value for ideally a 3-4 defense.

Bottom line, there has been less good than bad from this 49ers' defense that was supposed to take a step forward under Defensive Coordinator, Robert Saleh. DeForest Buckner, Fred Warner, and Richard Sherman have been positives but they haven't been enough to lift up the entire unit.

On offense, Matt Breida's ascension at running back has been a pleasant surprise as he leads the NFL in rushing with 274 yards. But he now has CJ Beathard under center instead of Jimmy Garoppolo.

With Beathard starting, the 49ers' flaws will be exemplified further. This team still had a lot of work to do even with Garoppolo. Now, without him, the front office may need to re-evaluate where they truly are in this rebuilding process, and make the necessary moves to take this team towards being a contender once again. Maybe a reality check is just what the 49ers needed, and that is likely what this team is about to get.