Going into Week 8 of the season, however, things have taken dramatically different turns for these two teams.
While the Browns are languishing at .500 and are better than expected in some ways, they clearly still have a long way to go.
The 49ers, by contrast, seem to have gotten it together faster than anyone expected despite having a rookie head coach, a questionable quarterback and what appeared to be a whole lot of weak points entering the season. After seven weeks of play, San Francisco is a surprising 5-1 and sitting atop the NFC West with a very comfortable lead.
As much as it may not have looked that way before the season started, winning this one will be a tough task for the Browns. Very tough.
And yet, while an upset isn't probable, it is possible. The Browns aren't the favorite here, nor should they be. But you know the saying, on any given Sunday...
Following are five ways the 49ers are vulnerable to an upset by the Browns. If Cleveland can take advantage of these, they just might have a shot to surprise San Francisco and get on the right side of .500 at the midpoint of the NFL season.
If I were a team with an elite passing game, I would be thrilled to face off with the 49ers, who have been underwhelming defensively against the pass, ranking 21st in the league and ceding 1,689 yards.
Unfortunately the Browns don't have an elite passing game, so this isn't quite as big a gift of a game for them.
However, the 49ers earned that lackluster 21st ranking mostly against teams who also are unimpressive in the effectiveness of their pass offense.
That means that if the Browns could just get a little something going in their aerial game, they too would have a chance to exploit San Francisco's weakness against the pass.
For this particular key to an upset, the Browns' fate is largely in their own hands. I know, I know...the Browns having their fate in their own hands screams fumble.
But we've seen flashes of great potential from Colt McCoy and Greg Little seems to get better and better every week (especially since he was given the starting nod two weeks ago), so the timing isn't awful for the Browns to be facing off with an opponent who, if the Browns play up to what we hope their potential is, is primed for a meltdown against an offense who attacks with a pass-heavy game plan.
For a team that appeared to have no viable options at quarterback before the season started, thing have worked out pretty well for the 49ers.
Alex Smith won't be getting anyone's Pro Bowl vote, but he's getting the job done and has his team sitting comfortably atop the NFC West at 5-1.
Smith has eight touchdowns on the season and just two interceptions, 1,090 yards and a 63.3 completion rating. Those numbers aren't stunning, but they're solid.
Still, he has vulnerabilities that the Browns have a good opportunity to exploit. Smith has fumbled three times on the season, so if the Browns can get to him the way they've been getting to other quarterbacks this season, they'll have a shot to not only render him ineffective, but force turnovers that could really help them out.
Also, shocking as it seems, the Browns are one of the worst defenses to be facing if you have a mediocre quarterback or a lack of depth at receiver. The Browns are second in the league against the pass with just 1,123 yards given up, and Smith has struggled against far less effective defenses.
His season high of 291 yards came against a terrible Philadelphia defense, and aside from that, he's broken the 200-yard mark just once.
However much the Browns can't seem to get credit from the football world at large for those few things they do actually do right, there's no arguing their ability to shut down opponents' passing games. I'm not sure that ranking would hold up against an elite passer like Drew Brees or Tom Brady or Aaron Rodgers, but I wouldn't bet against them facing off with a guy like Smith.
As rough as things have been for the San Francisco defense against the pass, they've been very good against the run.
They rank second in the league with just 448 yards ceded to opposing rushers. This is very bad news for a team like the Browns that has come to rely heavily on their ground game as the backbone of their offense.
Against a run defense this good, it would be foolish to try to push a rush-heavy strategy and hope to bowl them over despite their track record. I know there's something to be said for sticking to what works for you and not toying with your personal successful strategies to fit with a matchup, but I don't think that applies here.
That worked against Seattle, who they Browns correctly identified as overrated against the run. It won't work that way against San Francisco, whose defense against the run actually does look pretty legit.
This is especially true when Peyton Hillis will either be out or limited, and we have only one successful game thus far from Montario Hardesty to go on.
So the answer is to back off the run-heavy play-calling. The Browns need to learn to pick their battles in general, and this is a perfect example of one they should cede in order to gain an advantage on another front (their passing game).
Obviously the Browns can and should still go to the run in situations where that appears to be the favorable call, but for this game, even if this will never be the strategy going forward, they need to focus primarily on passing the ball and avoid running in any situation where it isn't absolutely necessary.
If they don't waste time and downs running futile rushing plays, they'll have more opportunities to exploit that weak pass defense the 49ers have and give themselves a far greater chance at an upset.
Perhaps the biggest key for the Browns to give themselves a chance at an upset this week lies in what their defense can do about RB Frank Gore.
He's an unfortunate Halloween weekend gift for the Browns' troubled run defense, because well, he's pretty darn scary.
Especially for a defense like the Browns, who, while solid on the whole, have struggled against the run and particularly against individual star-caliber rushers.
The Browns run defense is ranked 13th in the league, which feels deceptively high when you consider that they've given up 100-yard games to both Chris Johnson and Darren McFadden, and also been chipped away at by far less talented backs.
So to say the Browns have their work cut out for them with Gore is an understatement. Gore is by far the 49ers' greatest offensive weapon, logging 541 yards on 109 carries and scoring four touchdowns.
You can make the argument that he has been the most responsible party on offense for nearly every one of the 49ers' wins this season. That means if the Browns want to have a chance to send the 5-1 49ers to a rare defeat, they'll have to take down Gore, and they'll have to do it fast.
Gore is a player who can crush a defense with two big plays or slowly grind them down with 20-plus carries. If the Browns don't focus a huge amount of effort on figuring out how to stop him the way that they failed to do with McFadden and Johnson, he could single-handedly crush their hopes of an upset.
But if they can find a way to stop or at least seriously slow down Gore, they neutralize the 49ers' best offensive weapon and position themselves well for a shot at an upset.
Sad but true fact: Team who garner low expectations generally deserve it.
Most teams the Browns face don't take them seriously as an opponent, and you can't blame them for that. The Browns have managed to prove them right pretty often.
Still, being the underdog, if you can actually use it to your advantage, it is never a bad place to be.
Nobody expects the Browns to win this game. They have nothing to lose and everything to gain. And there's a good chance that the 49ers may make the same mistake as other teams who are tripped up by trap games and do not take their opponent seriously enough. And that could really open a door for the Browns for an upset.
Obviously drawing low expectations from your opponent doesn't do you a shred of good if you don't actually exceed them, and do so in a way that comes as a surprise to the opponent. So in order for this to work, the Browns would have to play above expectations, which has not exactly been their forte for many years.
Still, they won two games last season against New Orleans and New England because those teams underestimated them, and if they're at the top of their game this week, they could do the same thing to the 49ers.