When a stereo pair is formed from two synthesized views, it is unclear whether objective 2D quality metrics can provide a good estimation of the perceived quality. In this paper, this problem is addressed considering a 3D video represented in multiview video plus depth format. The performance of different state-of-the-art 2D quality metrics is analyzed in terms of correlation with subjective perception of video quality. A set of subjective data collected through formal subjective evaluation tests is used as benchmark. Results show that some objective metrics, including PSNR, do not predict well perceived quality of synthesized views. On the other hand, metrics such as VIF, VQM, MS-SSIM, or SSIM have a high correlation with perceived quality.