Lorenzo Cain 253 at bats with 65 hits= .257
David Lough 121 at bats with 38 hits= .314
Jarod Dyson 54 at bats with 15 hits= .278
Royals Total 428 at bats with 118 hits= .275
(Cain+Lough
+Dyson)
Wil Myers 58 at bats with 17 hits= .293
So far Wil Myers batting .293 with 428 at bats would have 7 more hits than what the the three Royals hit. One might be a home run and a couple would be RBIs.
Shields has pitched 117 innings with a 2.99 ERA. If his ERA was the Royals average of 3.57 it would mean he had given up another 7.4 runs.
If his ERA was the league average 3.92 it would be 11 runs instead of 7.4.
His 117 innings is 6th in the majors and his ERA is 24th.
A big part of the trade was that Tampa wanted to cut payroll and the Royals were willing to take Shields contract on, which we should celebrate.

Your logic is ridiculous, but I'll play your game. I'm bored.
Lough + Dyson + Cain = 7 HR's in 428 AB's
Wil Myers = 3 HR's in 58 ABs (which would be 22 HR's in the same amount of AB's)
Also.. You conveniently left out Frenchy.
Our OF if Myers was still here would be Gordon, Lough/Dyson, Myers
Myers - .293 BA, 3 HR's, 10 RBIs in 58 ABs (In 183 ABs - projected 9 HRs, 31 RBI's)
Frenchy - .208 BA, 3 HR's, 13 RBIs in 183 ABs
Even if we got a pitcher that was league average instead of Shields and gave up 11 more runs this season, if Myers would've played all season instead of Frenchy we would have 18 more RBI's. That's just with 183 AB's, we wouldn't have pulled Myers as much as Frenchy and he would probably have around 300 AB's.