I'd say they'd be warned for running down the middle of the wicket whilst taking a run.
The preamble regarding the spirit of cricket claims that umpires are the sole judges of fair and unfair play and are authorised to intervene in cases of damaging the pitch.
Law 40.11 - Damaging the pitch - area to be protected
(a) It is incumbent on all players to avoid unnecessary damage to the pitch. It is unfair for any player to cause deliberate damage to the pitch.
(b) An area of the pitch, to be referred to as 'the protected area', is defined as that area contained within a rectangle bounded at each end by imaginary lines parallel to the popping creases and 5ft/1.52m in front of each and on the sides by imaginary lines, one each side of the imaginary line joining the centres of the two middle stumps, each parallel to it and 1ft/30.48cm from it.
Law 40.14 - Batsman damaging the pitch
(a) If either batsman causes avoidable damage to the pitch, at the first instance the umpire shall, when the ball is dead,
(i) caution the batsman. This caution shall continue to apply throughout the innings. The umpire shall so inform each incoming batsman.
(ii) inform the other umpire, the other batsman, the captain of the fielding side and, as soon as practicable, the captain of the batting side.
(b) If there is a second instance of avoidable damage to the pitch by any batsman in that innings
(i) the umpire shall repeat the above procedure, indicating that this is a final warning.
(ii) additionally he shall disallow all runs to the batting side from that delivery other than the penalty for a No ball or a Wide, if applicable. The batsmen shall return to their original ends.
(c) If there is any further avoidable damage to the pitch by any batsman in that innings, the umpire shall, when the ball is dead,
(i) disallow all runs to the batting side from that delivery other than the penalty for a No ball or a Wide, if applicable. The batsmen shall return to their original ends.
(ii) additionally award 5 penalty runs to the fielding side. See 17 below.
(iii) inform the other umpire, the other batsman, the captain of the fielding side and, as soon as practicable, the captain of the batting side of what has occurred.
(iv) report the occurrence, with the other umpire, as soon as possible to the Executive of the batting side and any Governing Body responsible for the match, who shall take such action as is considered appropriate against the captain and player or players concerned.