By Tim Kelly, Sports Talk Philly editor 
Philadelphia Phillies starter and 2014 first-round pick Aaron Nola may currently be in the midst of his worst two month stretch in his young big league career, but one writer still believes that he is the most valuable piece currently on the Phillies.
In a piece where he named each team's 'most untouchable' player prior to the MLB's August 1 non-waiver trade deadline, ESPN's David Schoenfield wrote that Nola is the Phillies' most untouchable piece:
Who is the most untouchable player currently on the big league roster? Nola's 4.75 ERA isn't pretty and he has struggled lately, but his 3.06 FIP suggests there's a lot more upside than the ERA indicates.
As Schoenfield noted, the last two months haven't been pretty for Nola, but that shouldn't fool anyone into thinking he isn't still a bright part of the team's future. Through the first two months of the season, Nola had an ERA under three and looked as though he could represent the Phillies in the All-Star Game. The 23-year-old can't reach arbitration until 2019 and is under team control through 2021.
That said, while no one is debating that Nola is among the most valuable members of the Phillies, it is fair to ask whether he's the most untouchable piece.
Vince Velasquez, 24 and also under team control through 2021, is 8-2 with a 3.34 ERA in his first season with the Phillies. Velasquez has more overpowering stuff than Nola and seems to have a higher upside. However, he also had quite the injury history, perhaps giving him a lower long-term floor than someone like Nola just because of availability. This injury history, including a disabled list stint in 2016, seems to scare some fans. Following a report from Jon Morosi of FOX Sports that the Texas Rangers were interested in Velasquez yesterday, I conducted a highly unscientific poll on Twitter that saw over 55 percent of voters say that they would move Velasquez 'for the right price.' That statement is purposely vague, but it's safe to conclude that without injuries, the results to the poll would be very different. With the injury questions, some may view Nola as the more untouchable piece, even if his upside and trade value aren't as high.
Third baseman Maikel Franco also has to be factored into this discussion. Franco becomes eligible for arbitration in 2018, but the 23-year-old, like the two previously mentioned, cannot become a free-agent after the 2021 season. Franco is probably the most raw of anyone discussed in this article. He's shown flashes of potentially being an elite power hitter, though he has struggled to hit for power at home in his career, is batting at just .260 in 2016 and defensive metrics still aren't especially kind to him. The Phillies do lack another obvious power presence at the major league level though, and Franco isn't horrible at third base. The possibility also exists that in the long run he could either move to first base or become a designated hitter if that's introduced to the National League, and seeing as how he's likely to hit close to 30 home runs and 94 RBIs at 23, he can't be discounted.
The club's 2016 All-Star representative Odubel Herrera has posted a 2.2 WAR (per Fangraphs) this year, while hitting .286 with 11 home runs, driving in 56 RBIs and stealing 15 bases. While he's on pace to top many of the offensive stats from his rookie season a year ago, his once impressive defensive numbers have taken a dip in 2016. In 2015, Herrera posted an 11.7 dWAR, while Fangraphs says that he currently has a 0.2 dWAR in 2016. Herrera also placed fifth in UZR in 2015, while he's at just 12th currently. It's important to remember that the season is far from over and that Herrera is still relatively new to center field, but perhaps he won't develop into as good of a fielder as it once seemed he would. Herrera, like Nola and Franco, is 23, but unlike anyone mentioned in this article, he can become a free-agent after the 2020 season.
There probably isn't a clear answer to this question, which is indicative of the amount of the young talent the Phillies have. It's also indicative of the Phillies probably not having a truly untouchable player because there are so few of those around the league. Top prospect J.P. Crawford figures to be the answer to this question in a short time anyway, as the Phillies attempt to build a core of young talent that features a slew of coveted players.
