NFL free agency for a 49ers fan can be a frustrating time. Either the team doesn't do much of anything, or the moves they do make come off as uninspiring, to put it kindly. The team has a knack for signing players who have not lived up to their draft status or other expectations, something that aggravates fans to no end.

This year is no different, with guys like Blaine Gabbert and Jonathan Martin, as well as interest in former Minnesota Vikings CB Chris Cook. They were all first or second round draft picks but have done very little on the field in a positive way.

As fans get enraged by the team taking chances on these reclamation projects, it's good to note that this is not a new tactic...and also that it's worked-out quite well in the past. Let's take a look at a few of the 49ers past FA signings and how they were rated by Pro Football Focus, as well as keeping in mind that these guys were not popular in the court of public opinion at the time of their signing by the 49ers, either.

Again, PFF grades aren't everything, so keep in mind the widespread opinion on the player, one that you too probably held during the time he was signed. Let's all be honest about how we felt about these signings, and not have our perfect 20/20 hindsight convince us that we loved the acquisition all along.

First up is Carlos Rogers. That name may not inspire much confidence at this point, but at one point it did. It certainly wasn't when he initially came to the 49ers, as he had a 2010 PFF grade of -2.7 overall, including a -2.5 grade in coverage. Redskins fans complained that even if he was in the right place, he couldn't catch a cold, much less an INT. Free agency went on with CBs signing left and right, and there was Rogers, nobody wanting him.

Rogers had never cracked more than a 4.8 overall grade, usually hovering closer to a 2.x, since he came into the NFL. In his first season with the 49ers he had a whopping 14.4 overall, including a 9.2 in coverage, to go along with six interceptions and 18 passes defensed.

Granted Rogers' game fell back off again, but his past performance didn't preclude him from having a great season. Was he in the right place at the right time, aided by a fantastic front-seven? Sure. But he didn't cost the team, didn't lose them games, and performed well when given the chance.

Next we look at Donte Whitner, remember him? He's the guy who left for Cleveland and got top-10 safety money. When he came to San Francisco the team was laughed-at by Buffalo Bills fans. Whitner had a bad attitude, dealings with fans were not good, and his play on the field wasn't inspiring either.

In 2010 (the year prior to joining the 49ers) Whitner had a -0.7 grade from PFF, including a -3.7 in coverage. His 2009 wasn't any better, posting a -3.1 overall and a -4.1 in run defense, despite having a +3.2 in coverage. The 2008 grades were negative across the board, too.

Yet in Whitner's first year in San Francisco he posted a +13.5 overall grade to go with positives in both run defense and coverage. He also had two interceptions and 10 passes defensed, both career highs. By the time he knocked-out Pierre Thomas in the playoff tilt vs. the Saints, he had become a local legend.

In 2013 Whitner had one of his best seasons in pass coverage, posting a +12.7 grade (12.6 overall) and would go on to be thought of by many as one of the better safeties in the NFL. 49ers fans flocked to purchase "Legal Hitner" shirts, in support of the hits for which he was routinely penalized. Most didn't want to see him leave via free agency.

I would have also added Glenn Dorsey to this article, but honestly he was simply miscast as a pass-rusher in Kansas City, where is grades were awful in that regard, yet he was incredibly stout against the run. He simply didn't meet expectations as to what he'd be good at. The 49ers immediately recognized his strengths and put him to good use. I don't think he brought quite the negative opinions from Niner fans that the previous two guys did, so I didn't include him despite him coming in and having a monstrous season in San Francisco.

The underlying point here is that you can't take a guy's past and predict his future, at least not every time. The above are just two cases, but they serve to show that it's at least possible for a guy to re-make himself with the right situation, and the 49ers coaches seem to be pretty damn good at doing so.