And from 2001 through '04, Harbaugh experienced the wild swing in pressure as the Eagles went from a team that was challenging for the Super Bowl to one that had nothing left to accomplish but winning a Super Bowl.
It's a fascinating dynamic to watch.
Granted, things in Baltimore are not quite as edgy in Philadelphia when the Eagles first lost three consecutive NFC Championship Games and then came up short in Super Bowl XXXIX, but Harbaugh is entering that hot zone his old boss, Reid, has occupied for close to a decade now.
Like Reid, Harbaugh is becoming a victim of his own success after taking the Ravens to the playoffs in his first four seasons.
In a practical sense, Reid's 127-81-1 record and five NFC Championship Games during his Eagles tenure are solid testament to his ability as a coach.
But without a Super Bowl title, they have now become an albatross highlighting what he has not accomplished rather than accentuating what he has.
Harbaugh, who did not get the Ravens job until current Cowboys head coach Jason Garrett turned it down in 2008, has made the playoffs in each of his four seasons, winning at least 11 games three times and the 2011 AFC North championship.
But Harbaugh's Ravens lost in 2008 and '11 AFC Championship Games, and now Baltimore enters the 2012 season with only one measurement: get to the Super Bowl.
Although that's more unfair than fair, it is the reality of the Ravens' situation.
The cart is before the horse. Nothing that happens along the journey will matter unless the final destination is reached.
Frankly, for Harbaugh, the only thing worse than missing the playoffs would be if the Ravens went 12-4 and then came up short of the Super Bowl by losing in the playoffs.
"I feel as good about this team as any team we've had," he said recently. "That's not a predictor about our record or anything like that, but I really, really love this team."
Unfortunately for Harbaugh, that does become a predictor about the success of his team. The Ravens are coming off a 12-4 season where they lost a shot at the Super Bowl because of a last-second field-goal miss at New England.
The thing with professional sports is that "coming up short" can quickly transition into "not being able to get the job done" when it happens too many times.
After beating the Cincinnati Bengals on Monday, Harbaugh is 45-20 as a head coach. That's a winning percentage near 70 percent.
But with the Ravens coming to Lincoln Financial Field on Sunday for the Eagles' home opener, he didn't get long to enjoy it.
"Winning is a lot of fun," said Harbaugh, who is 1-0 against Reid. "[Monday] night in the locker room was great, but it's been a grind since.
"We've got a lot of work to do between now and [Sunday] to get ready. We need to improve on a lot things if we are going to go up [to Philadelphia] and compete against a very talented Eagles football team in a tough stadium."
We like to make a lot about this coaching-tree thing, but Harbaugh, like most assistants, is not a clone of the guy they worked under.
"Andy has been a huge influence," said Harbaugh, who is the brother of San Francisco 49ers coach Jim and son of former college coach Jack (Western Michigan, Western Kentucky). "He's been an influence on a lot guys. A number of guys off his staff have gone on to be head coaches. That's a great testament in and of itself to how he does things.
"I just have immense respect for what he's done, how he does it, and sure, it's impacted some of things we've done here."
The talk concerning Harbaugh in Baltimore isn't nearly as sharp as it is concerning Reid in Philadelphia.
The expectations are certainly rising, but he is still viewed as a coach who was off to great start in his first 4 years.
The two AFC Championship Game losses still are viewed as growing pains on the way to the ultimate goal.
But Harbaugh knows how quickly positives can swing into negatives.
He saw what has happened to Reid. He also knows it's really no different for any coach who achieves some measure of success but not the ultimate one.
"We have a confidence that whatever we do, it will be our best," Harbaugh said. "I feel we are talented and have a chance to be very good."
That works for now, but Harbaugh knows that it's just a matter of time before a consistent state of "very good" becomes indistinguishable from one that is "not good enough."
Contact John Smallwood at email@example.com. For recent columns, go to philly.com/Smallwood.