I've heard fans express the opinion that Michael Young is doing well this year: getting on base, being a professional hitter, and playing a surprisingly competent third base. While in the same breath bemoaning that Rollins is having a terrible year so far.
Is this really the case? Michael Young has largely delivered on what was expected. Many of us were quite concerned about what the Phillies might get from him this season. He is 36 and coming off a year in which he was quite literally the worst player in baseball to get regular playing time. And even before last year, he's been overrated, excelling in the higher profile stats like hits and batting average while falling short in areas that don't get as much scrutiny, like walks and fielding. But so far this year the Phillies could really not have asked for anything more than he's provided. A .287 average, along with the pleasant surprise of a very uncharacteristic 12.8% walk rate, have combined to put him on base at a .378 clip -- the 16th highest figure in the NL (and in the top 10 until just a couple of days ago).
Young's defense has not been atrocious, and he at least looks better than the worst case scenario that many were afraid of (i.e. something like 2012's Ty Wigginton). He's caught most of what's been hit at him, and has even made the occasional spectacular play. But his range is limited, and when taking all of his defensive contributions into account, he's been below average.
Rollins on the other hand is doing about what we expected: he's hitting close to the league average (wRC+ of 92), and playing better than average defense at a premium position.
Wins Above Replacement is a handy way to add up their contributions, and whether you use the version from FanGraphs (fWAR) or Baseball-reference (rWAR), Rollins has the higher WAR:
by fWAR: Rollins 0.8, Young 0.7
by rWAR: Rollins 0.5, Young 0.3
Their Fangraphs summaries:
Essentially Rollins' fielding advantage offsets Young's advantage at the plate, and Rollins gets about an additional 0.1 WAR bump for playing the more premium position.
In addition, they seem to be headed in different directions in recent weeks, as Young has cooled off, while Rollins' hitting has warmed up after his customary slow start. Rollins' career stats:
1st half: .263/.320/.410 (.317 wOBA, 90 wRC+)
2nd half: .277/.337/.461 (.344 wOBA, 107 wRC+)
Now, as we know, WAR is meant to be used as an approximation, and differences of tenths of a win are not really meaningful. All we can say is that Rollins so far would have the more credible claim for being more valuable.
His new contract proved to be a bargain in 2012, when (based on fWAR) he was the second best shortstop in the baseball. Even with the slow start, he seems to be on his way to earning the contract and then some again this season.