Take for instance the D-backs-Astros trade in December 2007.
The deal sent closer Jose Valverde to Houston in exchange for right-handers Chad Qualls and Juan Gutierrez and infielder Chris Burke.
The deal was somewhat controversial with D-backs fans, as Valverde was coming off a season in which he saved 47 games for the National League West champs.
It didn't help that in 2008, Valverde saved 44 games for the Astros while Burke hit just .194 and Gutierrez struggled in Triple-A, going 5-11 with a 6.09 ERA. Meanwhile Brandon Lyon had his share of struggles as Arizona's closer.
The only positive at that time for the D-backs was that Qualls performed well in a setup role with a 2.81 ERA and compiled nine saves in taking over for Lyon down the stretch.
"I never felt like I had any added pressure on me," Qualls said. "I just wanted to come in here and prove to everybody in the organization that I could pitch late in games and make everyone in the organization proud that they traded for me."
Based on the 2008 season, the trade seemed to overwhelmingly favor the Astros.
That perception began to change in 2009.
For one thing, injuries limited Valverde to 52 games, while Qualls pitched well as Arizona's closer, but more importantly, Gutierrez rebounded to become a force out of the bullpen.
In 65 games last year Gutierrez had a 4.06 ERA and he saved nine games, seven of which came while filling in for Qualls, who was injured at the end of August.
Valverde left Houston via free agency during the offseason, while the D-backs will have Qualls closing for them this year with Gutierrez in a setup role.
Suddenly a trade that may have looked lopsided one way has flipped.
"Jose pitched great for Houston," D-backs GM Josh Byrnes said. "Obviously, we knew we were trading two years of Jose for three years of Qualls and two additional players. A lot of our deals factor that in, how many years and at what cost. As we sit here today, two of our key relievers came in that trade and I think it achieved what it was supposed to for both sides."
It is amazing how close some of the numbers are for Valverde and Qualls since the deal was made. The two are nearly identical in each of the major categories and they've both converted 86 percent of their save chances.
"I keep my eye on Houston just because I played there," Qualls said. "And I knew that he had a couple of great years there. I didn't know the numbers were so eerily similar. It's pretty crazy."
Valverde hands down holds the edge in saves, 69-31, but Qualls did not become the D-backs closer until September of 2008.
Money and years of control an organization has over a player are important factors in evaluating almost any deal in baseball, and in this regard the D-backs without question came on top.
Valverde, who signed a two-year, $14 million deal with the Tigers during the offseason, made $12.7 million combined in 2008 and 2009. Meanwhile, Qualls, Gutierrez and Burke earned a combined $4.25 million over the same period.
Qualls is due to receive $4.19 million this year while Gutierrez, who is not eligible for salary-arbitration, will make just over the $400,000 league minimum salary.
While Qualls is eligible for free agency at the end of this season, Gutierrez cannot become a free agent until the 2014 season. If the D-backs lose Qualls at the end of the year and hang on to Gutierrez until he becomes a free agent, they will have gotten nine years worth of the pair while the Astros got two from Valverde.
"Trades are interesting because the most notable guys are easy to compare," D-backs manager A.J. Hinch said. "Then there's always those stragglers at the end of deals -- the player to be named later, the Minor League guy that doesn't get as much attention. In the scouting world and in the front office, people who have seen the players, it's easy to get excited when we got Gutierrez and, obviously, Qualls. You have to give up something and the goal is to get something in return.
"I don't know about the perception of trades. It's not my job to really worry about it. But the test of time is always the evaluation of the trade. The way Gutierrez has been, it turned out to be a nice deal for us."
First impressions may be hard to change, but they can also be misleading.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.