And yet, after all those outings, all those chances to learn, this might finally be the season that Detroit gets to see what kind of potential the young Porcello has. It's not just about the extra responsibility resting on his shoulders with Doug Fister gone, but the extra defense sitting behind him thanks to a retooled infield.
"He throws a lot of sinkerballs," team president/general manager Dave Dombrowski said, "and when he's at his best, he throws a lot of sinkerballs. Sometimes, perhaps, you try to overthrow and you try to do too much, but I think in his case, [he can] just pitch like he's normally pitched and he'll have a better defense behind him."
With free agency potentially awaiting Porcello in just two years, possibly putting him on the open market before his 27th birthday, the timing couldn't be better.
Although advanced metrics haven't been kind to the Tigers' defense in recent years, those same numbers became a strong defense for Porcello as a pitcher. Without saying a word, he has become the AL's poster child for Fielding Independent Pitching (FIP) as a measure of a starter.
FIP tries to take a team's defense out of a pitcher's evaluation and measure him simply on the plays he can control -- home runs, walks, hit-by-pitches and strikeouts. The rest of the plays, namely groundouts and flyouts, are no longer measured. The measurement is supposed to track like an ERA.
When Porcello won 14 games as a 20-year-old rookie, with a solid defense behind him, his ERA was stronger than his FIP. His four seasons since then have seen the numbers flip and the gap between the two grow.
Though Porcello's 4.32 ERA in 2013 was his best since that rookie season, his 3.53 FIP was easily the best of his career, resulting in a .79 gap -- his largest ever, according to Fangraphs.com. Tweak the stat even more and attach a standard home run rate for an expected FIP, and Porcello's 3.19 FIP was more than a full run lower than his ERA.
Only Cleveland's Justin Masterson had a higher ground-ball ratio among AL starters. Porcello gave up a .260 batting average on ground balls, 14 points above his career average, 18 points above his 2012 average and 58 points above his rookie average, according to baseball-reference.com.
The Tigers' pitching staff as a whole, meanwhile, gave up a .270 average on ground balls, 25 points above the AL average and 11 points higher than the next AL team.
Porcello's worst start of the season arguably served as a microcosm for the struggles. Of the nine hits Porcello gave up in his first -- and only -- inning against the Angels on April 20, six came on grounders, three on infield singles.
"If you ever looked at his numbers and took that outing away, his numbers are pretty darn good," Dombrowski said.
Considering the Tigers' rotation set an AL record for strikeouts in a season, the ground-ball average was a counterbalance. But the "Bill James Handbook" by Baseball Info Solutions uses a stat called Defensive Runs Saved to measure both individual fielders and teams. As a team, the formula argues, Detroit cost itself 63 runs in the field, third worst in the Majors and second in the AL, to the Mariners. Use only infielders, and the Tigers' minus-26 mark ranks fourth lowest in the AL, behind the White Sox, A's and Indians.
The one infield spot where Detroit had a positive rating was at shortstop, where Jhonny Peralta -- whose metrics often surpassed expectations -- and Jose Iglesias essentially split the campaign. But now, with Peralta in St. Louis and Iglesias expected to handle the job full-time, the runs-saved total could easily rise.
At second base, Texas' Ian Kinsler registered 11 runs saved last season, compared with a minus-5 rating for Omar Infante that seemed low for some of the plays he made. Prince Fielder's minus-13 rating at first base ranked lowest among Major League regulars, but that number should improve for the Tigers with Miguel Cabrera's move from third following Fielder's departure.
The more ground balls converted into outs, the better support for Porcello. What encourages Tigers officials just as much, though, is Porcello's ability to pitch for more than ground-ball outs. After Porcello dusted off his curveball with regularity last season for the first time since his rookie campaign, he recorded the best strikeout rate of his career. He threw curveballs on 16.5 percent of his pitches, the fourth-highest mark of any AL pitcher according to the "Bill James Handbook." Hitters swung and missed at 30 percent of the curveballs, according to STATS.
"He gets better and better and better," Dombrowski said. "His velocity picked up, and you can see his breaking ball got better."
With Fister now on the Nationals, Porcello has an opportunity to claim the fourth starter spot. And if he can continue his growth from here, he has a chance for more than that. Although Detroit faces a tough situation in regard to contract-extension talks for Max Scherzer, there's a decision to be made eventually on Porcello.
Though Porcello's age could allow him to hit the free-agent market well before his prime, it also could allow him to sign a contract extension and still test the waters at the peak age of most pitchers' careers. If the Tigers can't re-sign Scherzer, a new contract for Porcello could offer upside as an alternative.
"He's tough," Dombrowski said. "He's a hard worker. He's driven. We like him, and he's a battler, too. I wouldn't be surprised if there's more even in there as far as continuing to grow."
Porcello is done having to pitch for his immediate future. Now, even at his age, he could be pitching for the long-term, and he might have his best support behind him.