Rob Thomson's hand is finally forced with Phillies rotation thanks to injury

The Philadelphia Phillies continue to dominate the National League. There aren't too many notable points of weakness on the roster, but like several contenders around the league, that pesky fifth spot in the starting rotation could be better.

Dave Dombrowski has never been afraid to invest big money on a long-term basis. Most of the Phils' investments have worked out, but Taijaun Walker stands out as the rare misstep. In the second year of a four-year, $72 million contract, Walker continues to frustrate the fandom as Philadelphia's most inconsistent, at times downright abysmal starting pitcher.

The 31-year-old hasn't been able to build up much of a rhythm this season due to a series of injuries. Now, he's back on the 15-day IL as he deals with a "hot spot" — A.K.A., blister — on his pitching hand.

Walker told reporters he felt fine after four innings in Friday's loss to the Arizona Diamondbacks, but clearly he's not right. His fastball velocity averaged 90.5 MPH on Friday, a game in which Walker allowed three homers and four earned runs across four innings.

Phillies' Taijuan Walker moved to 15-day IL amid struggles

The injury thrusts Spencer Turnbull back into the spotlight for Philadelphia. Turnball started six games early in the season during Walker's first absence. The 31-year-old isn't the sexiest name in the sport, but few starter-reliever hybrids have been more effective this season. Across 16 total appearances and 51.1 innings pitched, Turnbull has a 2.63 ERA and 1.052 WHIP. Compared to Walker (5.60 ERA and 1.491 WHIP), Turnbull has been straight-up better.

Turnbull has a 0.9 WAR, compared to -0.4 WAR for Walker. All the stats (except for salary) favor Turnbull. There has long been a chorus of fans calling for Turnbull to permanently hold the fifth starting spot. Now, he gets a another chance to prove his mettle in the spotlight with Walker hurt.

Since the last time Turnbull objectively outperformed Walker didn't impact Rob Thomson's rotation, it's hard to say with any confidence that Turnbull has a chance to overtake Walker in the next couple weeks. But, with how thoroughly the Walker has struggled, Turnbull should be firmly in the mix moving forward. He gets a chance to face his former team on Wednesday in Detroit, which is a prime opportunity to make a statement.

It's never good to see a player hampered by injury, and there's no way Walker is excised from the rotation entirely. He has been coasting on resumé more than productivity of late, but perhaps a change to the rotational hierarchy would benefit all involved. Turnbull can occupy the fifth starting spot — Philadelphia is as strong as any team in baseball 1-4, with Cristopher Sanchez recently inked to a new four-year extension — while Walker gets to try his hand in a different role. It's worth a shot once the blister heals, especially if Turnbull delivers over his next couple starts.