  One of the intriguing puzzles concerning Swift J1644+57, the first jetted
tidal disruption event (TDE) discovered, is the constant increase in its jet
energy, as implied by radio observations. During the first two hundred days the
jet energy has increased by an order of magnitude. We suggest that the jet was
viewed slightly off-axis. In this case, the apparent energy increase arises due
to the slowing down of the jet and the corresponding broadening of its beaming
cone. Using equipartition analysis, we infer an increasing jet energy as a
larger region of the jet is observed. A simple off-axis model accounts nicely
for the multi-wavelength radio observations, resolving this long-standing
puzzle. The model allows us to self-consistently evolve the synchrotron
signature from an off-axis jet as a function of time. It also allows us to
estimate, for the first time, the beaming angle of the jet, $\theta_0 \approx
21^{\circ}$. Considering existing limits on the black hole mass, $\lesssim
10^{7}M_{\odot}$, this angle implies that the prompt phase beaming corrected
luminosity of Swift J1644+57, $\sim 10^{47}$ergs/sec, was super Eddington. We
also present a closure relation between the spectral and temporal flux for
off-axis jets, which can be used to test whether a given radio transient is
off-axis or not.
